Hacking

Experts found Symlink race issues in 28 antivirus products

Security experts from RACK911 Labs discovered “symlink race” vulnerabilities in 28 of the most popular antivirus products.

Security researchers from RACK911 Labs disclose the discovery of “symlink race” issues in 28 of the most popular antivirus products.

The flaws affect 28 products running on major OSs, including Linux, Mac, and Windows.

“A symlink race is a kind of software security vulnerability that results from a program creating files in an insecure manner. A malicious user can create a symbolic link to a file not otherwise accessible to them.” states Wikipedia. “When the privileged program creates a file of the same name as the symbolic link, it actually creates the linked-to file instead, possibly inserting content desired by the malicious user (see example below), or even provided by the malicious user (as input to the program).”

Symlink race vulnerabilities could be exploited to link malicious files to higher-privilege resources, allowing users to elevate privileges

The experts revealed that an attacker could exploit the vulnerabilities to delete files on the host, including the ones used by the antivirus or by the operating system, rendering the machine unusable.

Experts pointed out that most antivirus products work in a similar way, when an unknown file is saved to the hard drive, the software will usually perform a “real time scan, ” either instantly or within a couple of minutes. If the unknown file is a suspected threat, the file will be moved to a secure location used to quarantine the item.

Experts highlight that antivirus software run in a privileged state, an attacker that could exploit an issue in these solutions could potentially run code at the highest privileges. An attacker could perform a race condition via a directory junction (Windows) or a symlink (Linux & macOS) in the time between the initial file scan and the cleanup operation.

“What most antivirus software fail to take into consideration is the small window of time between the initial file scan that detects the malicious file and the cleanup operation that takes place immediately after.” reads the report published by the experts. “A malicious local user or malware author is often able to perform a race condition via a directory junction (Windows) or a symlink (Linux & macOS) that leverages the privileged file operations to disable the antivirus software or interfere with the operating system to render it useless, etc.”

RACK911 reported its findings to antivirus vendors and most of them have already addressed the flaws in their products (i.e. AVG, F-Secure, McAfee).

The experts also published proof-of-concept scripts that could exploit a (symlink) race condition issue to link malicious files to legitimate files via directory junctions (on Windows) and symbolic links (on Mac & Linux).

“In our testing across Windows, macOS & Linux, we were able to easily delete important files related to the antivirus software that rendered it ineffective and even delete key operating system files that would cause significant corruption requiring a full reinstall of the OS. (When targeting Windows, we were only able to delete files that were NOT currently in use; However, some antivirus software would still remove the file upon a system reboot.)” concludes the report.

The experts explained that it could be quite easy for attackers to exploit these issues.

Please give me your vote for European Cybersecurity Blogger Awards – VOTE FOR YOUR WINNERS
https://docs.google.com/forms/d/e/1FAIpQLSe8AkYMfAAwJ4JZzYRm8GfsJCDON8q83C9_wu5u10sNAt_CcA/viewform

[adrotate banner=”9″][adrotate banner=”12″]

Pierluigi Paganini

(SecurityAffairs – antivirus, hacking)

[adrotate banner=”5″]

[adrotate banner=”13″]

Pierluigi Paganini

Pierluigi Paganini is member of the ENISA (European Union Agency for Network and Information Security) Threat Landscape Stakeholder Group and Cyber G7 Group, he is also a Security Evangelist, Security Analyst and Freelance Writer. Editor-in-Chief at "Cyber Defense Magazine", Pierluigi is a cyber security expert with over 20 years experience in the field, he is Certified Ethical Hacker at EC Council in London. The passion for writing and a strong belief that security is founded on sharing and awareness led Pierluigi to find the security blog "Security Affairs" recently named a Top National Security Resource for US. Pierluigi is a member of the "The Hacker News" team and he is a writer for some major publications in the field such as Cyber War Zone, ICTTF, Infosec Island, Infosec Institute, The Hacker News Magazine and for many other Security magazines. Author of the Books "The Deep Dark Web" and “Digital Virtual Currency and Bitcoin”.

Recent Posts

Cisco addressed high-severity flaws in IOS and IOS XE software

Cisco addressed multiple vulnerabilities in IOS and IOS XE software that can be exploited to…

14 hours ago

Google: China dominates government exploitation of zero-day vulnerabilities in 2023

Google's Threat Analysis Group (TAG) and Mandiant reported a surge in the number of actively…

20 hours ago

Google addressed 2 Chrome zero-days demonstrated at Pwn2Own 2024

Google addressed two zero-day vulnerabilities in the Chrome web browser that have been demonstrated during…

1 day ago

INC Ransom stole 3TB of data from the National Health Service (NHS) of Scotland

The INC Ransom extortion group hacked the National Health Service (NHS) of Scotland and is threatening…

2 days ago

CISA adds Microsoft SharePoint bug disclosed at Pwn2Own to its Known Exploited Vulnerabilities catalog

U.S. Cybersecurity and Infrastructure Security Agency (CISA) adds a Microsoft SharePoint vulnerability disclosed at the…

2 days ago

The DDR Advantage: Real-Time Data Defense

This is the advantage of Data Detection and Response (DDR) for organizations aiming to build…

2 days ago

This website uses cookies.