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3 Articles

This Week In Security: Another Linux Exploit, Ubuntu Knocked Offline, Finals Interrupted, And Backdoored Tools

May 8, 2026 by 14 Comments

After the CopyFail vulnerability gave root access from any user on almost all distributions last week, this week we’ve got DirtyFrag. This chains the vulnerability in CopyFail (xfrm-ESP) and a new vulnerability in a RPC function which allows similar overwriting of the page cache.

Both vulnerabilities manipulate the Linux page cache where data from disk is stored for rapid access. The kernel will always prefer the cached version of a file, which means that anything that is able to manipulate the contents of the cache can effectively replace the contents of the file. Both of the vulnerabilities leverage a similar mechanism – picking a binary which is flagged to run as root, such as su, and replacing the contents that would prompt for the users password with a launcher to immediately run a shell.

Like CopyFail, DirtyFrag requires the ability to execute code on the target in the first place, but turning almost any code or command execution vulnerability in any network service into root raises the impact significantly, allowing an attacker to break out of containers and privilege environments, or establish a persistent presence in the system when the original vulnerabilities are discovered and closed.

The previous mitigations to block specific kernel modules related to CopyFail are not sufficient to block the new vulnerabilities. At the time of writing this, there are no available patches from the distributions, however the vulnerable kernel modules can be temporarily disabled.

CopyFail added to KEV

CISA (the United States cyber security agency) has added CopyFail to the KEV, or Known Exploited Vulnerabilities list. Attacks on the KEV have been observed under active exploitation, which in the case of CopyFail is hardly a surprise.

The KEV is designed as a tool to allow security teams in government and commercial industry to prioritize the highest risk vulnerabilities – or at least give another source of data to point at when you say “we really need to patch this now”.

Prolonged Ubuntu DDOS

On the heels of the CopyFail vulnerability impacting almost all distributions, Ubuntu has had to face a prolonged distributed denial-of-service (DDoS) attack against the main infrastructure. Ars Technica reported at the beginning of the attack, and after several days, services appear to be restored. In the meantime, core services such as package updates, core repositories, and even the Ubuntu and Canonical websites were largely unreachable.

An Iraqi group claims responsibility for the attack, but it is unclear if they were the actual perpetrators – or why. The timing with the CopyFail vulnerability seems like an opportune moment to cause chaos by taking the update mechanisms of a major distribution offline, but in the era of modern Internet behavior, it could also just have been a Tuesday.

Continue reading “This Week In Security: Another Linux Exploit, Ubuntu Knocked Offline, Finals Interrupted, And Backdoored Tools” →

Did TETRA Have A Backdoor Hidden In Encrypted Police And Military Radios?

July 27, 2023 by 42 Comments

Encrypted communications are considered vital for many organizations, from military users to law enforcement officers. Meanwhile, the ability to listen in on those communications is of great value to groups like intelligence agencies and criminal operators. Thus exists the constant arms race between those developing encryption and those desperately eager to break it.

In a startling revelation, cybersecurity researchers have found a potentially intentional backdoor in encrypted radios using the TETRA (TErrestrial Trunked RAdio) standard. TETRA equipment is used worldwide by law enforcement agencies, military groups, and critical infrastructure providers, some of which may have been unintentionally airing sensitive conversations for decades.

Continue reading “Did TETRA Have A Backdoor Hidden In Encrypted Police And Military Radios?” →

Serious Vulnerability In European Trunked Radio System

July 26, 2023 by 41 Comments

Trunked radio systems can be difficult to wrap one’s mind around, and that’s partially by design. They’re typically used by organizations like police, firefighters, and EMS to share a limited radio frequency band with a much larger number of users than would otherwise be able to operate. From a security standpoint, it also limits the effectiveness of scanners who might not know the control methods the trunked systems are using. But now a global standard for encrypted trunked radio systems, known as TETRA, has recently been found to have major security vulnerabilities, which could result in a lot more headache than disrupted voice communications.

One of the vulnerabilities in this radio system was a known backdoor, which seems to have been protected largely via a “security through obscurity” method. Since the system has been around for about 25 years now, it was only a matter of time before this became public knowledge. The backdoor could allow non-authorized users to snoop on encrypted radio traffic. A second serious vulnerability, unrelated to this backdoor, would further allow listening to encrypted voice traffic. There are a few other minor vulnerabilities recently uncovered by the same security researchers who found these two major ones, and the current recommendation is for anyone using a TETRA system to take a look to see if they are impacted by any of these issues.

Part of the reason this issue is so concerning is that these systems aren’t just used for encrypted voice among first responders. They also are used for critical infrastructure like power grids, rail networks, and other systems controlled by SCADA. This article from Wired goes into much more detail about this vulnerability as well, and we all know that most of our infrastructure already needs significant help when it comes to vulnerabilities to all kinds of failure modes.

Thanks to [cfacer] and [ToniSoft] who sent these tips!

Photo via Wikimedia Commons.