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UAT-4356 is an espionage-focused, likely government-backed threat actor tracked by Cisco Talos and associated with the ArcaneDoor campaign. Microsoft tracks this cluster as Storm-1849 and has described it as China-nexus. The actor has specialized in compromising network perimeter and security appliances, particularly Cisco ASA, Firepower, and Secure Firewall devices, to obtain durable access, visibility into sensitive traffic, and covert control from trusted infrastructure positions. UAT-4356 is publicly linked to the 2024 ArcaneDoor activity, in which Cisco ASA devices were compromised through zero-day exploitation. Subsequent activity showed continued focus on Cisco edge infrastructure, including exploitation of CVE-2025-20333 and CVE-2025-20362 against internet-facing Cisco firewall and VPN environments. In later intrusions, the actor deployed the custom FIRESTARTER backdoor and the LINE VIPER post-exploitation toolkit. The group’s tradecraft emphasizes stealth, in-memory execution, and abuse of legitimate device components rather than conventional endpoint malware deployment. FIRESTARTER is designed to run on Cisco security appliances, hook the LINA process, and execute attacker-supplied shellcode delivered through crafted WebVPN authentication traffic. The implant uses boot and mount-list manipulation to survive normal reboots and, in observed cases, remained effective even after patching and firmware updates, enabling the actor to regain access without re-exploiting the original vulnerabilities. Reporting on one confirmed federal civilian agency intrusion indicated months-long dwell time and re-entry after remediation efforts. LINE VIPER has been associated with post-compromise actions including shellcode loading, VPN authentication bypass, packet capture, credential and configuration access, suppression of logging, and broader operational support on compromised devices. This tooling, combined with FIRESTARTER’s persistence and LINA-level execution, indicates a mature capability for long-term cyberespionage against high-value network infrastructure. Known targeting has included government and critical national infrastructure networks, with a particular emphasis on exposed management and SSL VPN surfaces on perimeter devices. The actor’s operational pattern is consistent with strategic intelligence collection through compromise of edge appliances, allowing access to authentication flows, network traffic, and trusted administrative contexts. Known aliases include Storm-1849. UAT-4356 is most closely associated with ArcaneDoor, and its tooling has also been reported to share technical overlap with RayInitiator, suggesting continuity within the actor’s broader device-implant ecosystem.
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Who, where, and (when attributed) which flag flies behind the operation. Pulled from open-source reporting and Mallory's analyst review.
Sectors the actor has been observed targeting.
27 distinct techniques observed across reporting, grouped by tactic. Hover any cell for the evidence excerpt; click through for MITRE's full description.
5 malware families attributed to this actor across reporting.
4 CVEs this actor has used in observed campaigns. 4 of them exploited in the wild.
The attack chain begins with exploitation of known vulnerabilities (CVE-2025–20333, CVE-2025–20362) to gain initial access... CVE-2025–20333 (CVSS 9.9) affects the same WebVPN component and allows an authenticated remote attacker with valid VPN credentials to execute arbitrary code with root privileges. When combined, these vulnerabilities effectively enable unauthenticated remote code execution.
The attack chain begins with exploitation of known vulnerabilities (CVE-2025–20333, CVE-2025–20362) to gain initial access... CVE-2025–20362 (CVSS 6.5) is an unauthenticated URL access vulnerability in the VPN web server component of Cisco ASA/FTD. Attackers can access restricted URL paths without authentication, enabling session validation bypass, credential harvesting, or reconnaissance.
Cisco Talos previously attributed this group to the ArcaneDoor campaign in 2024, where they exploited two Cisco ASA zero-day vulnerabilities (CVE-2024–20353, CVE-2024–20359) to deploy malware such as Line Dancer and Line Runner.
Cisco Talos previously attributed this group to the ArcaneDoor campaign in 2024, where they exploited two Cisco ASA zero-day vulnerabilities (CVE-2024–20353, CVE-2024–20359) to deploy malware such as Line Dancer and Line Runner.
12 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
State-linked espionage-oriented activity cluster targeting Cisco Firepower, Secure Firewall, ASA, and FTD edge devices using chained vulnerabilities and custom implants for persistence, re-entry, credential harvesting, packet capture, and stealthy long-term access.
Conducting a targeted cyber-espionage campaign against Cisco network edge devices, deploying the custom FIRESTARTER backdoor on Cisco ASA, Firepower, and Secure Firewall appliances running FXOS to achieve stealthy, memory-resident access and long-term espionage.
Conducting a long-term intrusion campaign against Cisco ASA/FTD perimeter devices using the FIRESTARTER backdoor and LINE VIPER loader, with persistence designed to survive patching and reboots. The activity is linked to the earlier ArcaneDoor campaign and appears focused on intelligence collection via compromised network security appliances.
Espionage-focused activity targeting Cisco Firepower/FXOS perimeter devices by chaining known vulnerabilities to deploy the FIRESTARTER backdoor. The group was previously linked to the ArcaneDoor campaign and is using compromised network appliances for unauthorized remote control and espionage.
Match sector + geo + tech-stack targeting against your real footprint.
Every observed MITRE ATT&CK technique, grouped by tactic.
Families this actor is known to deploy, with IOCs and behavior.
CVEs this actor has used in known campaigns.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Domains, IPs, and hashes tied to this actor, refreshed continuously.