Interlock Ransomware Exploits Cisco FMC Zero-Day Vulnerability

A critical zero-day vulnerability, identified as CVE-2026-20131, in Cisco Secure Firewall Management Center (FMC) was actively exploited by the Interlock ransomware gang weeks before its public disclosure and subsequent patch in early March 2026. This significant cybersecurity event was brought to light by CJ Moses, Amazon's CISO and VP of Security Engineering. The revelation underscores the sophisticated and proactive nature of modern ransomware operations, which are increasingly leveraging undiscovered flaws to gain unauthorized access and initiate attacks before vendors can provide defensive measures.

According to Moses, Amazon's internal research, utilizing their advanced MadPot system of honeypots, detected Interlock's illicit activities targeting this specific flaw as early as January 26, 2026. This means the ransomware group had a substantial 36-day window of opportunity to exploit the vulnerability before Cisco officially disclosed and released a patch for it. The early detection by Amazon's honeypot system highlights the crucial role such defensive technologies play in identifying emerging threats and providing early warnings about zero-day exploits that bypass traditional security controls.

The risks associated with such a zero-day exploitation are profound, as organizations relying on unpatched Cisco FMC systems were unknowingly exposed to potential compromise by the Interlock ransomware. Attackers could have gained initial access, moved laterally within networks, and deployed ransomware, leading to significant data breaches, operational disruptions, and financial losses. This incident serves as a stark reminder of the continuous arms race between cyber defenders and attackers, emphasizing the critical need for rapid vulnerability response, continuous monitoring, and the deployment of advanced threat intelligence capabilities to mitigate the impact of sophisticated cyber threats like the Interlock ransomware.

(Source: https://www.helpnetsecurity.com/2026/03/20/cisco-fmc-interlock-ransomware-cve-2026-20131/)