Hackers Exploit Cisco SNMP Flaw to Deploy Rootkit on Switches: CVE-2025-20352

Estimated reading time: 8 minutes

Key Takeaways:

  • CVE-2025-20352 is a recently patched RCE vulnerability in Cisco IOS and IOS XE being actively exploited.
  • Attackers are deploying rootkits targeting older Linux systems lacking EDR solutions.
  • The rootkit can disable logging, bypass AAA and VTY ACLs, and move laterally between VLANs.
  • No readily available tool exists to reliably detect compromised Cisco switches; low-level firmware investigation is required.
  • Prioritize patching, network segmentation, and real-time threat intelligence to mitigate the risk.

Table of Contents:

CVE-2025-20352: Cisco SNMP Vulnerability Exploited

A recently patched remote code execution (RCE) vulnerability, CVE-2025-20352, affecting Cisco networking devices has been actively exploited by threat actors. These actors are deploying rootkits and targeting unprotected Linux systems. This activity underscores the importance of proactive security measures, including robust patch management, real-time ransomware intelligence, and comprehensive breach detection strategies.

The vulnerability lies within the Simple Network Management Protocol (SNMP) implementation in Cisco IOS and IOS XE. Successful exploitation of CVE-2025-20352 allows for RCE if the attacker possesses root privileges. This elevation of privilege grants the attacker significant control over the compromised system.

According to a report by Trend Micro, the attacks have specifically targeted Cisco 9400, 9300, and legacy 3750G series devices. The deployed rootkits primarily target older Linux systems lacking endpoint detection and response (EDR) solutions, highlighting the continued risk posed by legacy infrastructure. Cisco’s Product Security Incident Response Team (PSIRT) had previously flagged this vulnerability as being exploited as a zero-day.

Trend Micro researchers are tracking these attacks under the name “Operation Zero Disco,” a moniker derived from the malware’s practice of setting a universal access password containing the word “disco.” This naming convention aids in tracking and analyzing the specific characteristics of this campaign. The attackers also attempted to exploit CVE-2017-3881, a seven-year-old vulnerability in the Cluster Management Protocol code in IOS and IOS XE, revealing a pattern of leveraging both new and older vulnerabilities.

Rootkit Capabilities and Impact

The rootkit deployed through this exploit is equipped with several malicious capabilities. It uses a UDP controller that can be configured to listen on any port, providing flexibility for command and control. The rootkit can toggle or delete logs, effectively erasing traces of its activity. It can bypass AAA (Authentication, Authorization, and Accounting) and VTY ACLs (Virtual Terminal Access Control Lists), granting unauthorized access to network resources. The ability to enable or disable the universal password and hide running configuration items further enhances its stealth capabilities. Finally, it can reset the last write timestamp for files, complicating forensic analysis.

A simulated attack by Trend Micro researchers demonstrated the potential impact of a compromised system. Attackers could disable logging, impersonate a waystation IP address via ARP spoofing, bypass internal firewall rules, and move laterally between VLANs (Virtual Local Area Networks). This lateral movement capability is critical, allowing attackers to expand their reach within the network.

While newer switches are better protected due to Address Space Layout Randomization (ASLR), Trend Micro notes that they are not entirely immune. Persistent and targeted attacks could still compromise these systems, emphasizing the need for layered security. The rootkit installs hooks onto the IOSd process, causing fileless components to disappear after a reboot, further complicating detection and remediation efforts. Researchers were able to recover both 32-bit and 64-bit variants of the SNMP exploit, underscoring the adaptability of the threat actors.

Currently, there is no readily available tool that can reliably detect a compromised Cisco switch resulting from these attacks. The recommended approach for suspected compromises involves performing a low-level firmware and ROM region investigation, a resource-intensive and specialized task.

Practical Takeaways and Actionable Advice

For Technical Readers:

  • Patch Management: Prioritize patching vulnerable Cisco devices, specifically those running IOS and IOS XE. Ensure updates are applied promptly to mitigate the risk of exploitation of CVE-2025-20352.
  • Network Segmentation: Implement network segmentation to limit the lateral movement of attackers. VLANs can help isolate critical assets and prevent attackers from reaching sensitive areas of the network.
  • Intrusion Detection Systems (IDS) and Intrusion Prevention Systems (IPS): Deploy and maintain IDS/IPS solutions to detect and block malicious network traffic associated with rootkit activity. Configure alerts for suspicious SNMP traffic and unauthorized access attempts.
  • Log Monitoring: Implement centralized log monitoring to track system events and identify potential compromises. Pay close attention to log entries related to SNMP, AAA, and VTY access.
  • Firmware Integrity Checks: Regularly perform firmware integrity checks on Cisco devices to identify unauthorized modifications. Consider using tools that can verify the integrity of the ROM region.
  • Endpoint Detection and Response (EDR): Deploy EDR solutions on Linux systems to detect and respond to rootkit activity. Ensure that EDR solutions are up-to-date with the latest threat intelligence.
  • Disable SNMP if Unused: If SNMP is not required, disable it to reduce the attack surface.

For Non-Technical Readers (Business Leaders):

  • Resource Allocation: Ensure that the IT security team has the necessary resources to implement and maintain security controls. This includes budget for patching, monitoring, and incident response.
  • Security Awareness Training: Provide regular security awareness training to employees to help them identify and avoid phishing attacks and other social engineering tactics that could lead to system compromise.
  • Incident Response Plan: Develop and maintain a comprehensive incident response plan that outlines the steps to take in the event of a security breach. This plan should include procedures for identifying, containing, and eradicating threats.
  • Vulnerability Management: Implement a vulnerability management program to identify and remediate security vulnerabilities in a timely manner. This program should include regular vulnerability scans and penetration testing.
  • Risk Assessment: Conduct regular risk assessments to identify potential security risks and prioritize mitigation efforts. Focus on high-impact vulnerabilities that could have a significant impact on the business.
  • Cyber Insurance: Consider obtaining cyber insurance to help cover the costs associated with a security breach, such as incident response, legal fees, and regulatory fines.
  • Third-Party Risk Management: Implement a third-party risk management program to assess the security posture of vendors and partners who have access to sensitive data or systems. Consider implementing supply-chain risk monitoring solutions.

PurpleOps’s Role in Mitigating These Threats

PurpleOps provides a suite of services that can help organizations protect themselves from attacks exploiting vulnerabilities like CVE-2025-20352.

  • Cyber Threat Intelligence Platform: Our platform offers real-time ransomware intelligence and underground forum intelligence, providing early warnings about emerging threats and vulnerabilities. This allows organizations to proactively patch systems and implement security controls before attackers can exploit them.
  • Dark Web Monitoring Service: PurpleOps’s dark web monitoring service can detect compromised credentials and sensitive data leaked on the dark web. This information can be used to identify potentially compromised systems and take steps to prevent further damage.
  • Breach Detection: PurpleOps’s breach detection capabilities can identify malicious activity and potential security breaches. This allows organizations to respond quickly to contain the damage and prevent further spread of the attack.
  • Supply-Chain Risk Monitoring: PurpleOps offers supply-chain risk monitoring to assess the security posture of vendors and partners who have access to sensitive data or systems.
  • Brand Leak Alerting: PurpleOps’s brand leak alerting service monitors online sources for unauthorized use of an organization’s brand assets or confidential information.

By leveraging these services, organizations can significantly reduce their risk of falling victim to attacks exploiting vulnerabilities like CVE-2025-20352.

To learn more about how PurpleOps can help your organization improve its security posture, visit our platform or contact us at PurpleOps Solutions. Explore our red team operations, , supply chain information security, ransomware protection, and dark web monitoring capabilities to enhance your defenses. Consider leveraging our cyber threat intelligence services.

FAQ

Q: What is CVE-2025-20352?

A: CVE-2025-20352 is a remote code execution (RCE) vulnerability in the Simple Network Management Protocol (SNMP) implementation in Cisco IOS and IOS XE.

Q: What Cisco devices are affected?

A: The attacks have specifically targeted Cisco 9400, 9300, and legacy 3750G series devices.

Q: What can attackers do if they exploit this vulnerability?

A: Successful exploitation allows attackers to deploy rootkits, disable logging, bypass AAA and VTY ACLs, and move laterally between VLANs.

Q: How can I detect if my Cisco switch has been compromised?

A: Currently, there is no readily available tool. The recommended approach involves performing a low-level firmware and ROM region investigation.

Q: What steps can I take to protect my network?

A: Prioritize patching vulnerable devices, implement network segmentation, deploy IDS/IPS solutions, and monitor logs closely.