The Rise of Cyber Espionage: Unraveling the Intricate Web of Altered Cisco Devices

The Ongoing Saga of Compromised Cisco IOS XE Systems

Background

The recent compromise of Cisco IOS XE systems has taken a new turn, with security researchers observing a sharp decline in the number of infected systems over the weekend. The drop in compromised systems has sparked a range of theories among experts. However, researchers from Fox-IT have identified the real reason behind this decline: the attacker has simply altered the implant, making it invisible through previous fingerprinting methods.

The main bug in this exploit chain exists in the Web UI of IOS XE (CVE-2023-20198), ranking 10 out of 10 on the CVSS vulnerability-severity scale. It allows unauthenticated, remote attackers to gain initial access to affected devices and create persistent local user accounts. The exploit method also involves a second zero-day (CVE-2023-20273), which allows the attacker to elevate privileges to root and write an implant on the file system. Cisco released updated versions of IOS XE addressing the flaws on October 22, but the delay between disclosure and patch release gave cyber attackers ample opportunity to target unpatched systems.

Sudden Decline in Compromised Systems

Security researchers using tools like Shodan and Censys had reported a single threat actor infecting tens of thousands of affected Cisco IOS XE devices with an implant for arbitrary code execution. However, over the weekend, there was a sudden and dramatic drop in the number of compromised systems visible to researchers. This led to various speculations about the cause, including theories about a grey-hat hacker removing the implant, the attacker moving to another phase, or conducting a cleanup operation.

The reality, as discovered by Fox-IT, is that approximately 38,000 devices remain compromised through the two recently disclosed zero-day bugs. The attacker altered the implant to check for an Authorization HTTP header value before responding, leading to the decline in identified compromised systems. By using a different fingerprinting method, Fox-IT was able to identify the compromised devices that were still infected. They advised every Cisco IOS XE WebUI user to perform a forensic triage to identify compromised systems, referring to their advisory on GitHub for guidance.

Researchers from VulnCheck also confirmed that the compromised devices suddenly disappearing from view over the weekend aligns with Fox-IT’s findings. Cisco has updated its guidance for detecting the implant and released indicators of compromise after uncovering a variant of the implant that inhibits identification.

Motivations Behind the Attacker’s Actions

The motivation behind the attacker altering the implant remains puzzling to experts. It is unexpected for an attacker to openly maintain access to implants, especially when numerous security companies are aware of their existence. Some speculate that the username/password update made by the attacker is a short-term fix to hold on to the compromised systems until they can accomplish their goals or insert a more stealthy implant.

Editorial

This ongoing compromise of Cisco IOS XE systems highlights the pervasive and persistent nature of cyber threats. Despite the release of patches by Cisco, a significant number of devices remain compromised due to the delay between disclosure and patch availability. This further emphasizes the need for prompt patching and a sense of urgency when addressing critical vulnerabilities.

The attacker’s ability to modify the implant to evade detection highlights the cat-and-mouse game in the world of cybersecurity. As security researchers develop methods to detect compromises, attackers evolve their techniques to remain undetected. This underscores the importance of constantly updating and refining security measures to stay one step ahead of cybercriminals.

Additionally, the motivations behind the attacker’s actions raise questions about the inherent nature of hacking and cyber espionage. While it is often assumed that attackers go quiet after being exposed, this ongoing compromise demonstrates a different strategy. It appears that the attacker is engaged in a risky game, attempting to maintain access and control despite the increasing awareness of their activities.

Advice

Given the evolving nature of cyber threats, it is crucial for organizations and individuals to prioritize internet security. The compromise of Cisco IOS XE systems serves as a warning to regularly patch and update software to protect against known vulnerabilities. Promptly implementing the security recommendations provided by vendors is a proactive approach to mitigating risks.

Furthermore, organizations must adopt a comprehensive cybersecurity strategy that includes proactive threat hunting and continuous monitoring. Relying solely on pre-existing fingerprinting methods is not enough to detect sophisticated attacks. Regularly revisiting and enhancing detection techniques ensures a higher level of protection against evolving threats.

Lastly, the Cisco IOS XE compromise demonstrates the importance of sharing information and collaborating with security experts. By working together, researchers can identify ongoing attacks, share insights, and develop effective countermeasures. The cybersecurity community should continue to come together to address the shared challenge of defending against cyber threats.