Hackers Exploit Cisco SNMP Zero-Day to Deploy Rootkit on Switches
In October 2025, threat actors exploited a zero-day vulnerability (CVE-2025-20352) in Cisco networking devices, leveraging flaws in the Simple Network Management Protocol (SNMP) to gain remote code execution on affected IOS and IOS XE switches. Trend Micro reported that attackers primarily targeted Cisco 9400, 9300, and legacy 3750G series devices, deploying rootkits on switches and unprotected Linux systems. These rootkits established a persistent backdoor, allowing attackers to control device behavior, evade logging, bypass security controls, and move laterally across VLANs. Cisco acknowledged active exploitation and classified the issue as a zero-day, urging immediate firmware and ROM analysis if compromise is suspected. The incident highlights the continued targeting of network infrastructure via legacy vulnerabilities and sophisticated rootkits, as well as the pressing need for organizations to update detection capabilities, even on older or end-of-life systems. The use of unpatched infrastructure and the absence of robust endpoint detection provided attackers with a broad attack surface, underpinning the current urgency around zero trust networking and east-west traffic monitoring.
Kill Chain
