Placing Trust in Kicksecure

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Is Kicksecure trustworthy? Is there a backdoor in Kicksecure? How does Kicksecure protect itself from backdoors?

Introduction

Trust is a very problematic issue. This is the essence of why security is difficult in every field, including general computing and Internet communication. A skeptical user might ask themselves the following questions before relying upon Kicksecure for sensitive activities on a daily basis:

• Can Kicksecure and its developers be trusted?
• Are backdoors present in Kicksecure that can take control over a computer or exfiltrate data?
• Does Kicksecure generate compromised encryption keys to enable government spying?
• How trustworthy and sincere are the stated security goals of the Kicksecure project?

Opinions will vary widely, but the reasoning process used to reach the conclusion should be closely examined. It is important that both trust and distrust are based on facts, and not gut feelings, instincts, paranoid conceptions, unfounded hearsay or the words of others.

It is unsurprising that the Kicksecure project and other security platforms / tools claim to be honest, but written assurances are worthless. For an informed decision, it is worth looking at the bigger Kicksecure picture: core components, affiliations, project track record, and how reasonable trust might be established.

Freedom Software and Public Scrutiny

Kicksecure and other Freedom Software makes it possible to check the source code to determine how a software distribution functions and what it consists of. Suitably skilled individuals can thoroughly audit the code to search for the presence of any malicious code, like a backdoor. In addition, software can be manually built from source code and the result compared against any versions that are pre-built and already being distributed, like the Kicksecure ova images that can be downloaded from kicksecure.com. This comparison can determine whether any malicious changes were made, or if the distributed version was actually built with the source code.

Naturally most people do not have the requisite knowledge, skills or time to properly audit software. However, the public scrutiny of popular, open source software implies a certain degree of trustworthiness. The axiom attributed to Linus Torvalds -- "Given enough eyeballs, all bugs are shallow" -- is a reasonable assumption in user communities that are large, vibrant, and focused on fixing security vulnerabilities quickly. The Freedom Software community has a strong tradition of publicly reporting and resolving serious issues, and a large pool of developers and beta testers can help to identify and remedy problems.

The opposite of Freedom Software is non-freedom software. Freedom Software provides strong advangages over non-freedom software, which should be avoided. The case for Freedom Software is made on the avoid non-freedom software wiki page.

Table: Finding Backdoors in Freedom Software vs Non-Freedom Software

	Non-Freedom Software (precompiled binaries)	Freedom Software (source-available)
Original source code is reviewable	No	Yes
Compiled binary file can be decompiled into disassembly	Yes	Yes
Regular pre-compiled binaries	Depends	Yes
Obfuscation (anti-disassembly, anti-debugging, anti-VM) is usually not used	Depends	Yes
Price for security audit searching for backdoors	Very high	Lower
Difference between precompiled version and self-compiled version	Unavailable	Small or none
Reverse-engineering is not required	No	Yes
Assembler language skills required	Much more	Less
Always legal to decompile / reverse-engineer	No	Yes
Possibility of catching backdoors via observing incoming/outgoing Internet connections	Very difficult	Very difficult
Convenience of spotting backdoors	Lowest convenience	Very high convenience
Difficulty of spotting intentional, malicious backdoors	Much higher difficulty	Much lower difficulty
Difficulty of spotting a "bugdoor"	Much higher difficulty	Lower difficulty
Third parties can legally release a software fork, a patched version without the backdoor	No	Yes
Third parties can potentially make (possibly illegal) modifications like disabling serial key checks	Yes	Yes
Software is always modifiable	No	Yes
Third parties can use static code analysis tools	No	Yes
Third parties can judge source code quality	No	Yes
Third parties can find logic bugs in the source code	No	Yes
Third parties can find logic bugs in the disassembly	Yes	Yes
Benefits from population-scale scrutiny	No	Yes
Third parties can benefit from debug symbols during analysis	Depends	Yes
Display source code intermixed with disassembly	No	Yes
Effort to audit subsequent releases	Almost same	Usually lower
Forum discussion: Finding Backdoors in Freedom Software vs Non-Freedom Software

Spotting backdoors is already very difficult in Freedom Software where the full source code is available to the general public. Spotting backdoors in non-freedom software composed of obfuscated binaries is exponentially more difficult.

To further improve the situation in the future, the Freedom Software community is working on the Reproducible Builds project. Quote:

Reproducible builds are a set of software development practices that create an independently-verifiable path from source to binary code.

Whilst anyone may inspect the source code of free and open source software for malicious flaws, most software is distributed pre-compiled with no method to confirm whether they correspond.

This incentivises attacks on developers who release software, not only via traditional exploitation, but also in the forms of political influence, blackmail or even threats of violence.

This is particularly a concern for developers collaborating on privacy or security software: attacking these typically result in compromising particularly politically-sensitive targets such as dissidents, journalists and whistleblowers, as well as anyone wishing to communicate securely under a repressive regime.

Whilst individual developers are a natural target, it additionally encourages attacks on build infrastructure as an successful attack would provide access to a large number of downstream computer systems. By modifying the generated binaries here instead of modifying the upstream source code, illicit changes are essentially invisible to its original authors and users alike.

The motivation behind the Reproducible Builds project is therefore to allow verification that no vulnerabilities or backdoors have been introduced during this compilation process. By promising identical results are always generated from a given source, this allows multiple third parties to come to a consensus on a “correct” result, highlighting any deviations as suspect and worthy of scrutiny.

This ability to notice if a developer has been compromised then deters such threats or attacks occurring in the first place as any compromise would be quickly detected. This offers comfort to front-liners that they not only can be threatened, but they would not be coerced into exploiting or exposing their colleagues or end-users.

Several free software projects already, or will soon, provide reproducible builds.

Trusting Debian GNU/Linux

Nearly all the software shipped in Kicksecure comes from the Debian GNU/Linux distribution. Debian's packages are heavily scrutinized as it is one of the largest Linux distributions at present. Debian is also one of the most popular distributions for derivative platforms; Ubuntu Linux is a Debian derivative, and the same applies to all Ubuntu derivatives such as Linux Mint.

The sheer number using Debian's software packages and the large developer pool inspecting software integrity are significant factors in Debian's favor. Debian regularly identifies and patches serious security issues like the infamous SSH PRNG vulnerability , but backdoors or other purposeful security holes have never been discovered to date. Debian's focus on security is further evidenced by their Security Audit team which constantly searches for new or unfixed security issues.

Trusting Kicksecure

In one sense, Kicksecure is the simple union of Debian and Tor and a mechanism to glue them together. If a user already trusts Debian and The Tor Project, then a method for assessing Kicksecure trustworthiness is also necessary.

The Kicksecure project was founded on 11 January, 2012, see also history. As mentioned earlier, Kicksecure is Freedom Software which makes the source code available for inspection. In the main, Kicksecure is comprised of specifications for which Debian software packages should be installed and their appropriate configuration. See also this list of notable reviews and feedback about the security of Kicksecure.

With a relatively small development team and estimated user base, the "many eyeballs" theory may work against Kicksecure at present. However, the source code is comparably small and devoid of complexities, meaning the project is in relatively good shape compared to many other similar projects. Interested readers can learn more about the Kicksecure specification and design here.

With these factors in mind, the reader can now make an informed decision about the trustworthiness of Kicksecure.

Kicksecure Warrant Canary

Canary

The Kicksecure warrant canary is intended to provide a means of communication to users in the event Kicksecure is served with a secret subpoena, despite legal prohibitions on revealing its existence. For any canary in force, once the signature of the canary file is verified with OpenPGP and/or signify, this confirms that no warrants have been served on the Kicksecure project.

Note: the canary date of issue is represented by the gpg signature date. A new canary should be released within 4 weeks.

The canary and signature are available here:

• Canary text file: canary.txt
• OpenPGP signature: canary.txt.asc
• signify signature: canary.txt.sig

As a backup, the canary and signature are also available on github:

• https://github.com/Kicksecure/canary

Readers are reminded this canary scheme is not infallible. The canary declaration is provided without any guarantee or warranty, and it is not legally binding upon any parties in any form. The signer should never be held legally responsible for any statements made in the canary.

Related:

• Forum Discussion
• Dev/Warrant Canary Draft

Trusting Downloaded Images

Users should not blindly trust the Kicksecure project or its developers. Logically it is unwise to trust unknown persons, especially on the Internet. On that basis, trust in Kicksecure developers should not rely on his public persona or the appearance of the Kicksecure project alone. Kicksecure may be or could become a high profile target, and it is risky to assume that developer's build machines would remain clean under those circumstances.

Trusting the Download Location

Binary images can be trusted to some extent if a user verifies that they received exactly the same code as thousands of other users, and no one has found or publicly reported any serious security issues. This requires verification of the Kicksecure and Kicksecure images using the available OpenPGP signatures. All source code tags for releases are OpenPGP-signed by lead Kicksecure developer Patrick Schleizer.

In order of increasing security, the Kicksecure images can be:

1. Downloaded via https://www.kicksecure.com. TLS provides some trust and integrity of the hash file, but it is still advisable to check the site's certificate and perform digital software signature verification (instructions).
2. Downloaded over the Kicksecure v3 onion address with Tor Browser before digital software signature verification. Onion addresses provide a higher standard of authentication than clearnet addresses.
3. Built from source since it is a relatively easy procedure.

Trusting Kicksecure Images

Table: Maintainer Overview - Platform, Source Code, Binary Images, Permissions

	Kicksecure VirtualBox	Kicksecure KVM	Kicksecure for Qubes	Built from Source Code
Source Code Creation	Patrick	Patrick	Qubes project and Patrick	Patrick
Source Code Trust	Patrick	Patrick	Qubes project and Patrick	Patrick
Binary Image Creation	Patrick	HulaHoop	Qubes project	-
Binary Images Trust	Patrick	HulaHoop	Qubes project and Patrick	-
Package Upgrades Creation	Patrick	Patrick	Qubes project and Patrick	-

Since Kicksecure is based on Debian, Debian releases package upgrades. See also: Trusting Debian GNU/Linux.

Binary Images Policy

• A) Kicksecure binary image maintainers: Only the currently existing Kicksecure binary image maintainers are permitted to redistribute software forked binary builds of Kicksecure and advertise these on the kicksecure.com project website or forums.
• B) Unofficial software fork maintainers: Rebranding required. Change the project name Kicksecure and Kicksecure logo to something else, and host these on a different website to avoid confusing users about the origin of the software.

Reasons:

• Build verification: Verifiable Builds, let alone reproducible builds, let alone automatic verification of reproducible builds, rebuilders are unavailable and their availability many years ahead. In other words, the binary builds by Kicksecure are not yet verifiably created from project's own source code .
• Trust: Binary images unfortunately still require trust.
• Freedom Software rights: Others are welcome to exercise their right to software fork the Kicksecure project under the respective licenses. (Why Kicksecure is Freedom Software)
• No additional restrictions: There is no restriction of software redistribution rights under the respective licenses. (Kicksecure:Copyrights)
• Trademark: Kicksecure is a trademark, see Kicksecure Trademark Policy.
• Reputation: To protect the reputation of the Kicksecure project, quality control, non-maliciousness, potential Evil Developer Attack.
• Fork friendly: Kicksecure is Software Fork Friendly.
• Common practice: Trademark protection is commonplace even for Freedom Software. For example, see Tor Project, which also develops Freedom Software, The Tor Project Trademark Policy or Debian Trademark Policy, Ubuntu, Red Hat, Fedora and most if not all Linux distributions doing the same which can easily be seen by a web search for the name of the Linux distribution and trademark.

A reasonable process on how new Kicksecure binary image maintainers could be securely admitted is yet to be developed. Please start a new Kicksecure forum thread if you are interested to develop the process and/or to become a Kicksecure binary image maintainer.

Please contribute towards Kicksecure source code generally or specifically towards verifiable builds, reproducible builds and rebuilders so the trust requirement can be removed from the equation.

Builds from Source Code versus Builds including Binary Packages

What "building from source code" means in the context of building Linux distributions from source code is not well defined. To explain the situation for Kicksecure, it is first important to mention the general, unspecific situation for other Linux distributions.

Rhetoric exercises left for the reader:

1. Build a Debian installer ISO completely from source code without using any binary packages from packages.debian.org. Unfortunately, this is difficult. There was once a bounty Build Debian Packages from Source Code worth $3000 USD, but no implementation was ever contributed. See also How to update all Debian packages from source code?, DebianBootstrap, and rebootstrap.

   In this context, bootstrapping refers to building binaries for an architecture from source without using any pre-built binaries for that architecture. In the past 20 years, about 20 architectures have been bootstrapped for Debian. At all times this has been a manual and non-repeatable process. rebootstrap is trying to address the very early bootstrap phase involving the gcc/eglibc dance.

2. Install Debian using an installer ISO (from completely source code) without using any binary packages from packages.debian.org.
3. Upgrade Debian completely from source code without using any binary packages from packages.debian.org.
4. Using any Debian (from source code or not): Build and install from source code while also acquiring all the build dependencies without using any binary packages from packages.debian.org. apt-build is the closest approximation of that but it uses binary packages from packages.debian.org to fulfill build dependencies. The development of apt-build stalled and the package was orphaned.
5. Build any Qubes template image or a Qubes installer ISO from source code without using any binaries from deb.qubes-os.org. This will probably be very difficult or impossible without Qubes source code modifications. Qubes build script function installQubesRepo enables deb.qubes-os.org, i.e., binary packages from deb.qubes-os.org are used during the Qubes build process.
6. Attempt the previous example but without using packages.debian.org and its Fedora equivalent.
7. Attempt to upgrade an installed Qubes installation using Qubes source code only without using any binary packages from qubes-os.org.
8. Create your own packages.debian.org, deb.kicksecure.com, and/or deb.qubes-os.org under a different domain name or on local disk.

All of the above tasks are very difficult tasks for which unfortunately very little documentation exists. Even description and awareness of the issues rarely exist. These issues are, however, unspecific to Kicksecure. These are mentioned to explain the context and set realistic expectations of what the Kicksecure project might be able to provide. The situation in Kicksecure is as follows:

• Kicksecure:
  • Builds: When Kicksecure is built from source, no contents from kicksecure.com are used and no binaries created by the Kicksecure project are used. However, unfortunately running the Kicksecure build script results in using binary packages from packages.debian.org. This is because Kicksecure inherits the same limitations as the above examples mentioning Debian.
  • APT repository: No issues with Kicksecure APT Repository Default Settings.
  • Upgrades from source code: There is a wiki page Upgrading Kicksecure Deb Packages from Source Code and a locally-upgrade-debian-packages but, see footnote.
• Kicksecure-Qubes: Inherits the same limitations as the above examples mentioning Qubes. Unfortunately, binary packages from packages.debian.org, deb.kicksecure.com, and deb.qubes-os.org are used.

Undeniably, this situation is unsatisfactory. In the future, reproducible builds and rebuilders will hopefully reduce or eliminate the requirement to trust binaries.

Asking about these issues will very most likely not result in people writing documentation on how to accomplish these very difficult tasks. The only realistic option to improve this situation is to contribute to reproducible builds and/or build from source code-related projects.

Related:

• Trusting Downloaded Images
• Kicksecure Updates
• Software Update APT Repository Security
• Software Build Process Security
• Malware and Firmware Trojans
• Malware Audits

Trusting the Kicksecure Website

Web Application Shortcomings

As noted in the Privacy on the Kicksecure Website chapter, the following separate web-based platforms are currently in use:

1. Discourse for the Kicksecure forums.
2. MediaWiki for online documentation.

The problem is these web applications (web apps) are developed independently from Kicksecure. This means Kicksecure developers have little to no control over the course these projects take. Since privacy and security issues often take a back seat to "enhanced features", websites relying on these or similar web apps can at best only provide privacy by policy, which is equivalent to a promise.

It is infeasible from a monetary, time and manpower perspective to address perceived shortcomings in these web apps. This means the Kicksecure community should not place undue trust in the live version of this site on the Internet, due to the potential for interference.

Distrusting Infrastructure

In an identical fashion to the Qubes project, Kicksecure has adopted the principle that all infrastructure should be explicitly distrusted. Infrastructure in this context refers to "...hosting providers, CDNs, DNS services, package repositories, email servers, PGP keyservers, etc."

Third parties who operate infrastructure are "known unknowns" and potentially hostile. It is safer to voluntarily place trust in a few select entities, such as the contributors of Kicksecure packages, the holder(s) of Kicksecure signing keys and so on. By sufficiently securing endpoints, it is unnecessary to try and improve the trustworthiness of those operating the "mid-points". This also provides two benefits: Kicksecure forgoes the need to invest valuable resources on the problem, and no illusory security expectations are raised in the Kicksecure community.

Quote Qubes OS (security-focused operating system):

What does it mean to “distrust the infrastructure”?

A core tenet of the Qubes philosophy is “distrust the infrastructure,” where “the infrastructure” refers to things like hosting providers, CDNs, DNS services, package repositories, email servers, PGP keyservers, etc. As a project, we focus on securing endpoints instead of attempting to secure “the middle” (i.e., the infrastructure), since one of our primary goals is to free users from being forced to entrust their security to unknown third parties. Instead, our aim is for users to be required to trust as few entities as possible (ideally, only themselves and any known persons whom they voluntarily decide to trust).

Users can never fully control all the infrastructure they rely upon, and they can never fully trust all the entities who do control it. Therefore, we believe the best solution is not to attempt to make the infrastructure trustworthy, but instead to concentrate on solutions that obviate the need to do so. We believe that many attempts to make the infrastructure appear trustworthy actually provide only the illusion of security and are ultimately a disservice to real users. Since we don’t want to encourage or endorse this, we make our distrust of the infrastructure explicit.

Also see: Should I trust this website?

Self-Hosting vs Third Party Hosting

Some users mistakenly believe that servers of security-focused projects are virtually impenetrable and hosted in the homes of developers; this is not the case. The kicksecure.com server is actually hosted at an Internet hosting company. Similarly, The Tor Project and Tails servers are not hosted in a developer's home either. Hosting at home is the exception, rather than the rule. At the time of writing, there are no known cases where servers are hosted in a developer's home. This means employees of the associated Internet hosting company have physical access rights to the server, along with any other capable, malicious actors.

Since virtually every project is hosted by a third party (an Internet hosting company), the capability to physically secure server hardware is largely forfeited. Without physical security and due to the risk of untrusted visitors, a hardware backdoor could easily compromise the security of the server.

Any demand that servers ought to be super secure and hosted in a developer's home is idealistic. Home Internet connections are generally too slow to meet the requirements of a public web server in terms of traffic quota and connection upload speed. Internet service providers (ISPs) do not usually allow a busy public web server to be hosted on home connections; throttled connections or terminated contracts are likely if that happens.

The "proper solution" would require purchase of a business Internet uplink, similar to becoming an Internet hosting company. This would incorporate a business building with a good Internet uplink, full camera security, security officers and so forth. Unfortunately this is economically infeasible at the current stage of project development.

Security Level

Many web applications in use by kicksecure.com did not provide software signatures at the time of installation or still do not provide them. Therefore, in stark contrast to software installed by default in Kicksecure, for the kicksecure.com server it was not possible to always enforce verification of software signatures.

Many web application and extensions updaters did not, or still do not, securely verify software signatures. Therefore, the security level of most servers is probably only equivalent to plaintext. In the case of the kicksecure.com server, the system security level is only equivalent to always use TLS and not always use software signatures verification.

Server Privacy

In the past, various suggestions for "perfect server privacy" were made such as "self-hosting in developers' homes" or "host the server outside the five eyes (nine eyes, fourteen eyes) countries". Despite the good intentions, these suggestions do not easily translate into an actionable plan.

First, these suggestions assume there is a sane method of rating the privacy protections afforded by a specific country. Moreover, the privacy rights granted for local citizens in a specific jurisdiction do not necessarily extend to non-citizens. Kicksecure developers are unaware of any project that rates privacy protections in this way, considers the feasibility of operating servers (by running tests), and then makes recommendations for locations which provide the best possible privacy.

In today's world following the Snowden disclosures, it has to be assumed that if surveillance is possible it is being done. The likelihood is that surveillance is undertaken in all jurisdictions, and it is only a matter of degree.

Even The Tor Project -- a much older, established and better funded organization -- does not attempt to implement any suggestion concerning "perfect server privacy". As noted on their sponsor's page:

Fastly generously hosts our Tor Browser update downloads that can be fetched anonymously.

Fastly is providing content delivery network (CDN) services and is headquartered in America (arguably the most aggressive member of the five eyes network). Even Debian uses CDNs Amazon AWS and Fastly.

In a similar fashion to the Distrusting Infrastructure chapter, Kicksecure has concluded it is not worthwhile investing valuable resources to try and provide "perfect server privacy", because it is simply uneconomical. For this reason, the viewpoint that no undue trust should be placed in the server arrangements is made explicit.

Onion Domain Name

kicksecure.com provides an alternative onion domain name.

Onion addresses provide a higher standard of authentication than clearnet addresses.

Onion services offer strong authentication via multiple layers of encryption. This does not prohibit an advanced adversary from trying to impersonate an onion service, but together with multiple fingerprint sources, it becomes increasingly difficult and improbable that a single entity could impersonate them all.

Due to server security issues this however might be negated in part. For example, consider:

• How realistic is it that an adversary could break TLS, but not the server?
• How realistic is it that the kicksecure.com clearnet domain name gets suspended, but the server provider stays online? This is related to Legal Issues.

related: Forcing .onion on Project

Server Security

Server security issues should not be conflated with software security issues. If an advanced adversary wanted to tarnish the reputation of any security-focused project, then breaking into the data center where it was hosted and "hacking" them would be one way to achieve that aim. Projects that are honest need to mention this possibility beforehand, so it is not unexpected.

The world's largest and most profitable technology companies like Google, Facebook, Microsoft and Amazon can easily afford to employ large, dedicated and skilled teams of system administrators to work around the clock to protect their servers. For small projects, this scale of server protection is completely unrealistic.

Software Update APT Repository Security

A compromise of the kicksecure.com server would not result in a compromise of users attempting to upgrade Kicksecure. This is because of a standard APT security feature: digital signature verification of APT repository metadata (SecureApt). An adversary who compromised the kicksecure.com server would lack the signing key required to generate valid signed APT repository metadata. Invalid APT repository metadata would be rejected by the user's APT updater software. APT repository metadata is signed locally on the developer's computer before the signed metadata is uploaded to the kicksecure.com server. The Kicksecure APT repository signing key is never exposed to the server. Thanks to digital signature verification the Kicksecure software update APT repository can be in theory considered more secure than than the kicksecure.com website.

Software Build Process Security

A compromise of the kicksecure.com server would not result in a compromise of software packages (image downloads, Debian packages, .debs) because all software is built locally on the developer's computer. No binary builds offered to download for users of software developed under the Kicksecure umbrella is ever created on remote servers hosted by third parties. Users who always correctly verify software signatures could detect malicious software before use. However, note these Consequences of Server Compromise.

Server Privacy vs Server Security

In an ideal world, both server privacy and server security would be maximized at the same time. However, in the real world this is an impossibility.

In a world with specialization and division of labour, those companies who excel at hosting web applications have more focus, time, energy, knowledge and money to work on server security; it is their raison d'etre (reason for being). In contrast, small projects use web applications only as a means to an end. Therefore, using third party web application hosters may provide better security than self-hosting, but better server privacy demands self-hosting. This means it is impossible to optimize both security and privacy simultaneously; the goals are at odds with each other.

Server Downtime

The almost perfect uptime of popular web services such as Google, Facebook, and Amazon (perhaps 99.99 per cent) might lead some to conclude this is an easy goal to achieve; this is a false assumption.

Expecting the same uptime from much smaller projects like Kicksecure is unrealistic. At best, maybe only 99.0 per cent uptime can be provided because no resources are spent on server uptime statistics, server upgrades need to be performed, and reboots are necessary. These factors necessarily lead to downtime when the website is unavailable. With a huge budget it would be possible to approach the 99.99 per cent uptime that popular websites have via technical solutions such as server farms, load balancing, and failover, but this is infeasible for small projects. Similarly, large companies can afford to pay for whole teams of system administrators who are working 24/7, in concert with these technical options. Again, small projects do not have that option.

Finally, server downtime is not evidence of a server compromise, but normally relates to server issues (for example, failing hard drives) and routine server maintenance.

Consequences of Server Compromise

A compromised kicksecure.com would result in one or more of the following issues:

• Provision of poor and/or malicious advice to visitors of the kicksecure.com website.
• Offer malicious software downloads to users who do not always verify software signatures.
• Unavailability of legitimate software downloads and updates.
• Reputational damage for Kicksecure.

Conclusion

Due to the multiple issues outlined in this section, the software produced by the Kicksecure project is theoretically considered more secure than the website provided by the Kicksecure project (kicksecure.com). The Kicksecure software is the main product delivered by the Kicksecure project, while the kicksecure.com server is only a tool to document and deliver Kicksecure. For further reading on this topic, see: Website and Server Tests.

OpenPGP

Introduction

• Digital signatures are a tool enhancing download security. They are commonly used across the internet and nothing special to worry about.
• Optional, not required: Digital signatures are optional and not mandatory for using Kicksecure, but an extra security measure for advanced users. If you've never used them before, it might be overwhelming to look into them at this stage. Just ignore them for now.
• Learn more: Curious? If you are interested in becoming more familiar with advanced computer security concepts, you can learn more about digital signatures here digital software signatures.

Fingerprint Trust

Most users retrieve OpenPGP fingerprints directly from a website and then download an associated key from a key server. The problem with this method is that TLS is fallible and the connection could be insecure or broken. Greater security necessitates a key signing party, whereby a direct and trusted path of communication can be confirmed by all attendees. If this step is not followed, OpenPGP is only secure as TLS.

It is often impossible to meet this condition of meeting in person. To mitigate the risk, any OpenPGP fingerprint should be cross-referenced on multiple "secure" (https://) sites. An additional fail-safe is to use an alternative authentication system, for example comparing the Tor signing keys on both the clearnet and .onion domains.

Onion services offer strong authentication via multiple layers of encryption. This does not prohibit an advanced adversary from trying to impersonate an onion service, but together with multiple fingerprint sources, it becomes increasingly difficult and improbable that a single entity could impersonate them all.

Kicksecure Binaries and Git Tags

All Kicksecure binaries are OpenPGP-signed by Kicksecure developer Patrick Schleizer. The source code is directly available on github over TLS, and it can be cloned using git over https://. Git tags for each release are also OpenPGP-signed by Kicksecure developer Patrick Schleizer. Users can also request signed git development tags from the same developer.

Even if Kicksecure developers are distrusted, verifying binary downloads or git tags with OpenPGP is still useful. For example in order to audit Kicksecure, it is important to verify the download came from Kicksecure developers and that it was not tampered with by third parties. This is a realistic threat, as these recent examples show:

• An attacker could modify source codes on github
• sourceforge hacked
• sourceforge mirror hacked

The OpenPGP key also ensures that if the Kicksecure infrastructure is ever compromised by a powerful adversary (such as a domain takeover), the original Kicksecure developers can at least prove they owned the infrastructure.

Kicksecure Developer OpenPGP Guidelines

All long-term Kicksecure developers are encouraged to:

• Create a 4096/4096 RSA/RSA OpenPGP key.
• Retrieve the latest gpg.conf which comes with Kicksecure for stronger hashes, no-emit-version, and other improved settings.
• Store the private key inside an encrypted file.
• Make a backup of that encrypted file.
• Remember the password and regularly test one's memory of it.
• Upload the encrypted file to a (free) online cloud-based host to protect against theft, fire, natural events and so on.

From the beginning of the Kicksecure project, greater trust has been placed in developers who publish their OpenPGP public key earlier on, since this reduces the probability of an evil developer attack.

Kicksecure Updates

Introduction

When it comes to trust, there is a large difference between building Kicksecure from source code and using the Default-Download-Version.

APT Repository and Binary Builds Trust

When Kicksecure is built from source code using the build script and the source code is audited by the builder to be non-malicious and reasonably bug-free, Kicksecure developers are unable to access the system. On the other hand, if Kicksecure APT repository is enabled, developers holding a Kicksecure repository signing key could release a malicious update to gain full access to the machine(s).

Even if the Kicksecure APT repository is not used with the Default-Download version, it is still theoretically possible for Kicksecure developers to sneak a backdoor into the binary builds which are available for download. Although an unpleasant threat, using Kicksecure APT repository poses a greater risk: a malicious Kicksecure developer might sneak in a backdoor at any time.

It is easier to sneak backdoors into binary builds, since they contain compiled code in binary packages which are downloaded from the Debian repository when built.

APT Repository Default Settings

Kicksecure:

• Building from source code: Kicksecure APT Repository is disabled by default.
• Default binary download: Kicksecure APT Repository is enabled by default.

Kicksecure-Qubes:

• Qubes/Install: Kicksecure APT Repository is enabled by default.
• Building from source code: Kicksecure APT Repository is enabled by default.

Most users will have the Kicksecure APT repository enabled. This means when updated Kicksecure debian packages are uploaded to the Kicksecure APT repository, these packages will be automatically installed when the system is upgraded. If this behavior is unwanted, this can be disabled. Refer to the previous section outlining security implications before proceeding.

Security Conclusion

Legend:

• *: poor security.
• ****: best security.

Table: Build and APT Repository Security Comparison

	Binary Download with Kicksecure APT Repository	Binary Download without Kicksecure APT Repository	Built from Source Code and Kicksecure APT Repository Enabled	Built from Source Code and Kicksecure APT Repository Disabled
Security	*	**	*	****
Convenience	****	*	**	*

In summary:

• The Kicksecure binary download using the Kicksecure APT repository is the most convenient method, but also the least secure.
• It is somewhat safer to use the Kicksecure binary download and then disable the Kicksecure APT repository. However, the user must then manually download updated Kicksecure deb packages upon release, and independently verify and install them.
• The greatest security comes from building Kicksecure and updated packages from source code, particularly if the source code is verified before building Kicksecure.

Appendix

What Digital Signatures Prove

• Digital signatures are a tool enhancing download security. They are commonly used across the internet and nothing special to worry about.
• Optional, not required: Digital signatures are optional and not mandatory for using Kicksecure, but an extra security measure for advanced users. If you've never used them before, it might be overwhelming to look into them at this stage. Just ignore them for now.
• Learn more: Curious? If you are interested in becoming more familiar with advanced computer security concepts, you can learn more about digital signatures here digital software signatures.

See Verifying Software Signatures for details on what digital signatures prove.

In short, a user must be careful to ensure the public keys that are used for signature verification are the Kicksecure key pair belonging to the Kicksecure developer of the component specific component. At time of writing there are two different components and signing keys.

• Kicksecure Main, APT Repository and Source Code Signing Key

TLS

TLS, SSL and HTTPS are all flawed since they rely on the vulnerable Certificate Authority (CA) model; see here for further details and SSL/TLS alternatives.

Evil Developer Attack

Introduction

An "evil developer attack" is a narrow example of an insider threat:

Software development teams face a critical threat to the security of their systems: insiders.

[...]

An insider threat is a current or former employee, business partner, or contractor who has access to an organization’s data, network, source code, or other sensitive information who may intentionally misuse this information and negatively affect the availability, integrity, or confidentiality of the organization’s information system.

In the case of software, a disguised attack is conducted on the integrity of the software platform. While this threat is only theoretical, it would be naive to assume that no major software project has ever had a malicious insider. Kicksecure and all other open source software projects face this problem, particularly those that are focused on anonymity such as VeraCrypt, Tails, I2P, The Tor Project and so on.

Attack Methodology

A blueprint for a successful insider attack is as follows:

1. Either start a new software project or join an existing software project.
2. Gain trust by working hard, behaving well, and publishing your sources.
3. Build binaries directly from your sources and offer them for download.
4. Attract a lot of users by making a great product.
5. Continue to develop the product.
6. Make a second branch of your sources and add malware.
7. Continue to publish your clean sources, but offer your malicious binaries for download.
8. If undetected, a lot of users are now infected with malware.

An evil developer attack is very difficult for end users to notice. If the backdoor is rarely used, then it may remain a secret for a long time. If it was used for something obvious, such as adding all the users to a botnet, then it would be quickly discovered and reported on.

Open source software has some advantages over proprietary code, but certainly not for this threat model. For instance, no one is checking if the binaries are made from the proclaimed source and publishing the results, a procedure called "deterministic builds". This standard is quite difficult to achieve, but is being worked towards.

Related Attacks

While most security experts are focused on the possibility of a software backdoor, other insider attacks can have equally deleterious effects. For instance, the same methodology can be used to infiltrate a targeted project team but in a role unrelated to software development; for example, as a moderator, site administrator, wiki approver and so on. This approach is particularly effective in smaller projects that are starved of human resources.

Following infiltration, disruption is caused within the project to affect productivity, demoralize other team members and (hopefully) cause primary contributors to cease their involvement. For example, using a similar blueprint to that of the evil developer attack, a feasible scenario is outlined below:

1. Join an existing software project as a general member.
2. Gain trust by working hard, behaving well, assisting readily in forums, making significant wiki contributions and so on.
3. Attract a lot of community admiration by outwardly appearing to be a bona fide and devoted project member.
4. Eventually attain moderator, administrator or other access once team membership is extended.
5. Continue to behave, moderate and publish well.
6. Once trust is firmly established, subtly undermine the authority, character and contributions of other team members.
7. If the insider threat is undetected for a significant period, this can lead to a diminished software product due to a fall in contributions in numerous domains and team ill will.

Conclusion

The insider threat nicely captures how difficult it is to trust developers or other project members, even if they are not anonymous. Further, even if they are known and have earned significant trust as a legitimate developer, this does not discount the possibility of serious mistakes that may jeopardize the user. The motives and internal security of everyone contributing to major software projects like Tor, distribution developers and contributors, and the hundreds of upstream developers and contributors is a legitimate concern.

The trusted computing base of a modern operating system is enormous. There are so many people involved in software and complex hardware development, that it would be unsurprising if none of the bugs in existence were intentional. While detecting software changes in aggregate may be easy (by diffing the hash sums), finding and proving that a change is a purposeful backdoor rather than a bug in well designed source code is near impossible.

Legal Issues

The following is not legal advice and does not refer to any specific laws; it is a theoretical consideration by non-lawyers.

Users occasionally raise the possible privacy and security implications if contemporary, draft laws were to be passed. For example, how the Kicksecure project would react to laws:

• banning end-to-end encryption
• outlawing anonymity tools like Tor
• demanding that operating systems include a backdoor

It is important to note that government members have diverse and conflicting interests. Bills which are hostile to Internet privacy and security are regularly introduced in various jurisdictions, but common sense usually prevails and ill-conceived legislation normally stalls and fails to become law. Conversely, bills that allocate funding to support cryptographic development and privacy tools garner support and are normally passed because most legislators understand their importance in an open society. While Internet privacy advocacy groups should remain vigilant, it is unproductive to become unduly stressed whenever a bill hostile to privacy or security is proposed.

Although it may be counter-intuitive, in the event privacy-hostile laws are passed this is not a Kicksecure-specific issue, even though Kicksecure would obviously be affected. For the most part, Kicksecure is a compilation of existing software packages provided by third parties which allow re-use in a compilation due to permissive licensing (Freedom Software). In this context, noteworthy components which Kicksecure relies on directly or indirectly are the base operating system (Debian at time of writing) and an anonymizer (Tor at time of writing). At first, such a law would very likely harm the security properties of these and other projects (see footnote).

Legal Jurisdiction

In response to the possibility of privacy-hostile laws being implemented, it is usually suggested that the Kicksecure legal entity should relocate to a different country. The effectiveness of moving to another jurisdiction would of course depend upon the specifics of the legal text, however it is unlikely that simple legal loopholes would exist. For example, legal entity relocation does or did not help people who would like to sell controlled substances (such as medicine) or goods (such as weapons) without all authorizations required by law. Another example are financial services; this is also why unnamed stock certificates on the blockchain do not exist.

Some U.S. laws apparently apply to all international jurisdictions. Take the case of Kim Dotcom who is a German/Finnish dual national. Although a permanent resident of and physically present in New Zealand at the time of alleged copyright infringement charges brought forth by the USA, he had his assets seized, worldwide bank accounts frozen, was arrested, and is fighting extradition to the USA. As Kim Dotcom summarized on Twitter:

I never lived there
I never traveled there
I had no company there

But all I worked for now belongs to the U.S.

How The US Government Legally Stole Millions From Kim Dotcom

Legal Compliance

Sometimes it is suggested to simply not comply with new laws impacting privacy, however this is an unreasonable request. Most laws include an enforcement mechanism, although it can be selectively applied depending on government interests. Serious penalties apply if a law is not being complied with, especially for repeat and continuous offenses. Penalties may include:

• imprisonment
• monetary fines
• for failure to pay monetary fines, the threat of asset seizure, imprisonment or worse

Law enforcement has incredibly long arms. In most cases there is no way to openly defy the law for an extended period and get away with it. To a large degree policy issues cannot be fixed only via technological means; it must be combined with peaceful resistance on a political level. Government policy is affected by popular opinion, and those who support privacy-enhancing technologies can help the cause by sharing their reasoned opinions with others. Casual supporters are also important to raise public awareness.

Even if privacy-hostile laws are in place, it might still be permitted to contribute Open Source code to Open Source projects. For example, perhaps only the person(s) redistributing binary builds to the public would be held personally accountable. This is pure speculation until a new draft law catastrophic to security software eventuates.

If Kicksecure was ever forced to add a backdoor by law, users would be notified and the project would be shut down before the law took effect. Fortunately, as yet there are no outrageous law proposals that would force the continued running of backdoored projects. In this case, efforts might focus on a new Linux-based project centered on stability, reliability, documentation, recovery, and usability.

Forum discussion:
EU Wants To Create Device/OS Level Backdoor

Other Projects Discussing Trust

• Tails is a live CD or USB that aims to preserve privacy and anonymity - Tails about trust.
• I2P (anonymizing network) has also discussed development attacks.
• Qubes OS: What digital signatures can and cannot prove
• Miron’s Weblog: Attack Scenarios on Software Distributions
• A list of incidents concerning compromised servers: On distributing binaries
• https://forum.qubes-os.org/t/qubes-os-could-be-honeypot/16180

License

Kicksecure Trust wiki page Copyright (C) Amnesia <amnesia at boum dot org>
Kicksecure Trust wiki page Copyright (C) 2012 - 2024 ENCRYPTED SUPPORT LP <adrelanos(at)kicksecure.com (Replace (at) with @.)Please DO NOT use e-mail for one of the following reasons: Private Contact: Please avoid e-mail whenever possible. (Private Communications Policy) User Support Questions: No. (See Support.) Leaks Submissions: No. (No Leaks Policy) Sponsored posts: No. Paid links: No. SEO reviews: No. >

This program comes with ABSOLUTELY NO WARRANTY; for details see the wiki source code.
This is free software, and you are welcome to redistribute it under certain conditions; see the wiki source code for details.

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