Malicious Code in XZ Utils for Linux Methods Permits Distant Code Execution

Apr 02, 2024NewsroomFirmware Safety / Vulnerability

The malicious code inserted into the open-source library XZ Utils, a extensively used bundle current in main Linux distributions, can also be able to facilitating distant code execution, a brand new evaluation has revealed.

The audacious provide chain compromise, tracked as CVE-2024-3094 (CVSS rating: 10.0), got here to mild final week when Microsoft engineer and PostgreSQL developer Andres Freund alerted to the presence of a backdoor within the information compression utility that provides distant attackers a option to sidestep safe shell authentication and achieve full entry to an affected system.

XZ Utils is a command-line software for compressing and decompressing data in Linux and different Unix-like working techniques.

The malicious code is claimed to have been intentionally launched by one of many mission maintainers named Jia Tan (aka Jia Cheong Tan or JiaT75) in what seems to be a meticulous assault spanning a number of years. The GitHub person account was created in 2021. The id of the actor(s) is presently unknown.


“The threat actor started contributing to the XZ project almost two years ago, slowly building credibility until they were given maintainer responsibilities,” Akamai stated in a report.

In an extra act of intelligent social engineering, sockpuppet accounts like Jigar Kumar and Dennis Ens are believed to have been used to send feature requests and report a wide range of points within the software program so as to power the unique maintainer – Lasse Collin of the Tukaani Challenge – so as to add a brand new co-maintainer to the repository.

Enter Jia Tan, who launched a collection of adjustments to XZ Utils in 2023, which ultimately made their option to launch model 5.6.0 in February 2024. In addition they harbored a complicated backdoor.

“As I have hinted in earlier emails, Jia Tan may have a bigger role in the project in the future,” Collin said in an alternate with Kumar in June 2022.

“He has been helping a lot off-list and is practically a co-maintainer already. 🙂 I know that not much has happened in the git repository yet but things happen in small steps. In any case some change in maintainership is already in progress at least for XZ Utils.”

The backdoor impacts XZ Utils 5.6.0 and 5.6.1 launch tarballs, the latter of which comprises an improved model of the identical implant. Collins has since acknowledged the mission’s breach, stating each the tarballs have been created and signed by Jia Tan and that they’d entry solely to the now-disabled GitHub repository.

“This is clearly a very complex state-sponsored operation with impressive sophistication and multi-year planning,” firmware safety firm Binarly said. “Such a complex and professionally designed comprehensive implantation framework is not developed for a one-shot operation.”

XZ Utils for Linux

A deeper examination of the backdoor by open-source cryptographer Filippo Valsorda has additionally revealed that the affected variations permit particular distant attackers to ship arbitrary payloads by means of an SSH certificates which shall be executed in a fashion that circumvents authentication protocols, successfully seizing management over the sufferer machine.

“It appears as though the backdoor is added to the SSH daemon on the vulnerable machine, enabling a remote attacker to execute arbitrary code,” Akamai stated. “This means that any machine with the vulnerable package that exposes SSH to the internet is potentially vulnerable.”


For sure, the unintended discovery by Freund is without doubt one of the most vital provide chain assaults found so far and will have been a extreme safety catastrophe had the bundle been built-in into steady releases of Linux distributions.

“The most notable part of this supply chain attack is the extreme levels of dedication of the attacker, working more than two years to establish themselves as a legitimate maintainer, offering to pick up work in various OSS projects and committing code across multiple projects in order to avoid detection,” JFrog said.

As with the case of Apache Log4jthe incident as soon as once more highlights the reliance on open-source software program and volunteer-run initiatives, and the results that would entail ought to they endure a compromise or have a serious vulnerability.

“The bigger ‘fix’ is for organizations to adopt tools and processes that allow them to identify signs of tampering and malicious features within both open source and commercial code used in their own development pipeline,” ReversingLabs said.

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Author: (The Hacker Information)
Date: 2024-04-02 09:18:00

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Alina A, Toronto
Alina A, Toronto
Alina A, an UofT graduate & Google Certified Cyber Security analyst, currently based in Toronto, Canada. She is passionate for Research and to write about Cyber-security related issues, trends and concerns in an emerging digital world.


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