Hackers Exploit Cisco SNMP Flaw to Deploy Linux Rootkits

CVE-2025-20352 vulnerability security illustration — Photo by Fer Troulik on Unsplash

Cybersecurity researchers have revealed a concerning campaign known as Operation Zero Disco, which exploits the CVE-2025-20352 vulnerability affecting Cisco IOS Software and IOS XE Software. This significant security flaw allows hackers to deploy Linux rootkits on older, unprotected systems. The CVE-2025-20352 vulnerability, which has a CVSS score of 7.7, is a stack overflow vulnerability in the Simple Network Management Protocol (SNMP) implementation of Cisco’s software.

Details of the CVE-2025-20352 Vulnerability

The CVE-2025-20352 vulnerability is particularly alarming as it targets the SNMP protocol, which is commonly used for network management. By exploiting this flaw, attackers can execute arbitrary code on affected devices, leading to unauthorized access and potential control over the systems. This vulnerability affects various versions of Cisco IOS and IOS XE, which are widely used in enterprise environments. As a result, many organizations may be at risk if they have not updated their systems to address this critical issue.

Trend Micro’s research indicates that the hackers behind Operation Zero Disco are specifically targeting older Cisco devices that have not been patched against this vulnerability. This highlights the importance of keeping software up to date, especially for systems that play a vital role in network infrastructure. The deployment of Linux rootkits can further compromise these systems, allowing attackers to maintain persistent access and potentially launch further attacks against connected networks.

Impact of Linux Rootkits on Affected Systems

The impact of deploying Linux rootkits via the CVE-2025-20352 vulnerability can be severe. Once a rootkit is installed, it can allow attackers to manipulate system operations without detection. This can lead to data breaches, loss of sensitive information, and disruption of services. For organizations, the presence of a rootkit can compromise the integrity of their network, leading to significant financial and reputational damage.

Moreover, the risks are not limited to the immediate threat of unauthorized access. The exploitation of this vulnerability can also lead to broader implications for user privacy. As attackers gain control over network devices, they may intercept and manipulate data traffic, potentially exposing sensitive user information. This is particularly concerning for VPN users, who rely on secure connections to protect their online activities. If the underlying network infrastructure is compromised, the effectiveness of a VPN can be significantly undermined.

Context

The discovery of the CVE-2025-20352 vulnerability and its exploitation in Operation Zero Disco comes at a time when cybersecurity threats are becoming increasingly sophisticated. As organizations continue to adopt more complex network architectures, the potential attack surface for malicious actors expands. This highlights the need for continuous monitoring and proactive security measures to safeguard against emerging threats.

What to do

To mitigate the risks associated with the CVE-2025-20352 vulnerability, organizations and individuals should take immediate action:

Update all affected software to the latest versions immediately to close security gaps.
Enable automatic updates where possible to ensure timely patching of vulnerabilities.
Monitor security advisories from Cisco and other affected vendors for updates and guidance.
Use a VPN service like ProtonVPN or NordVPN to protect your internet traffic from potential interception.
Consider implementing additional security measures, such as multi-factor authentication, to enhance overall security posture.