Static Tundra Fuels Espionage Campaigns Through an Old Cisco Bug

Static Tundra Cyber Espionage Campaign Targeting Cisco Devices

Summary

Static Tundra, a Russian state-sponsored cyber espionage group tied to the Federal Security Service (FSB), has been actively exploiting Cisco network devices since 2021. Known as a sub-cluster of the Energetic Bear (Crouching Yeti/Dragonfly/Havex) threat actor, Static Tundra leverages advanced implants and custom malware to gain long-term, stealthy access across North America, Asia, Africa, and Europe. Targeted industries include telecommunications, higher education, and manufacturing. At the core of its campaign is the exploitation of CVE-2018-0171 in Cisco IOS Smart Install, enabling persistent access, espionage, and covert operations.

Attack Details

Static Tundra has focused its operations on compromising outdated or unpatched Cisco network devices. The group exploits CVE-2018-0171, a Cisco IOS and IOS XE Smart Install remote code execution vulnerability, to harvest configurations, steal credentials, and deploy durable backdoors.

One of the group’s most dangerous tools is SYNful Knock, a malicious firmware modification that establishes a stealthy, modular backdoor activated via crafted packets. This makes detection and removal extremely difficult.

To strengthen persistence, Static Tundra creates privileged accounts, modifies SNMP community strings, alters TACACS+ authentication, and employs advanced implants to automate exploitation and data theft. Once inside, the group pivots deeper into networks, compromising additional devices and maintaining espionage access for years.

Recommendations

1. Smart Install and Version Validation – Use show vstack config to check for Cisco Smart Install status and validate running software versions with show version. Cisco’s IOS Software Checker should be used to identify affected releases.

2. Cisco-Specific Hardening – Disable Telnet, restrict administrative interfaces (SNMP, SSH, HTTP/HTTPS), enforce Type 8 passwords for local accounts, and use Type 6 encryption for TACACS+ keys.

3. Logging and Monitoring – Continuously monitor syslog and AAA logs, track NetFlow/port scanning anomalies, and review .bash_history files for unauthorized activity.

4. Configuration & Access Management – Implement regular configuration audits, enforce strict authentication controls, review access control lists (ACLs), and ensure centralized configuration management.

Indicators of Compromise (IoCs)

• IPv4 Addresses:

  • 185[.]141[.]24[.]222

  • 185[.]82[.]202[.]34

  • 185[.]141[.]24[.]28

  • 185[.]82[.]200[.]181

MITRE ATT&CK TTPs

• Tactics: Reconnaissance (TA0043), Resource Development (TA0042), Initial Access (TA0001), Execution (TA0002), Persistence (TA0003), Privilege Escalation (TA0004), Defense Evasion (TA0005), Credential Access (TA0006), Discovery (TA0007), Lateral Movement (TA0008), Exfiltration (TA0010), Command and Control (TA0011).

• Techniques: Exploit Public-Facing Application (T1190), Modify System Image (T1601), Exploitation of Remote Services (T1210), Network Service Discovery (T1046), Credential Access in Files (T1552.001), Non-Standard Port (T1571), Exfiltration Over Alternative Protocol (T1048), among others.

References

• Talos Intelligence – Static Tundra

• IC3 PSA August 2025

• Cisco Software Checker

• Talos Scanner

• Google Cloud – SYNful Knock

• Hive Pro Threat Advisory – Salt Typhoon