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UNC5337 is a China-nexus cyberespionage cluster known for compromising Ivanti Connect Secure VPN appliances. Its activity dates to at least January 2024, and it has been associated with zero-day exploitation of CVE-2025-0282, an unauthenticated stack-based buffer overflow permitting remote code execution. Associated campaigns have targeted organizations across multiple countries and sectors, including automotive, chemicals, government, financial services, and telecommunications. UNC5337 deploys the custom SPAWN malware ecosystem to establish stealthy, persistent access to compromised appliances. Its tools include SPAWNSNAIL, an SSH backdoor with process-injection capabilities; SPAWNMOLE, a tunneler that hooks process communications to provide proxy access; SPAWNANT, an installer that persistently deploys other SPAWN components and can install additional web shells; and SPAWNSLOTH, a utility that suppresses appliance logging. These components support remote access, traffic tunneling, movement into internal networks, and defense evasion. Its operations emphasize maintaining long-term access to internet-facing VPN infrastructure while reducing visibility through log tampering.
Mallory correlates actor tradecraft and target patterns against your stack, your sector, and your geography. See overlap before they land.
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.
Geographies tied to known operations.
Attributed origin per open-source reporting.
11 distinct techniques observed across reporting, grouped by tactic. Hover any cell for the evidence excerpt; click through for MITRE's full description.
8 malware families attributed to this actor across reporting.
3 additional families tracked in Mallory.
4 CVEs this actor has used in observed campaigns. 4 of them exploited in the wild.
CVE-2025-0282, a zero-day vulnerability, has been exploited since December 2024, enabling unauthenticated remote code execution.
UNC5221 is a suspected China-nexus actor that Mandiant is tracking as the only group exploiting CVE-2023-46805 and CVE-2024-21887 during the pre-disclosure time frame since early Dec. 2023.
UNC5330 has been observed chaining CVE-2024-21893 and CVE-2024-21887 to compromise Ivanti Connect Secure VPN appliances as early as Feb. 2024. Post-compromise activity by UNC5330 includes deployment of PHANTOMNET and TONERJAM.
Similarly, CVE-2025-22457 is also attributed to a stack-based buffer overflow weakness. This vulnerability impacts a range of Ivanti products, including Pulse Connect Secure 9.1x and Ivanti Connect Secure 22.7R2.5 and earlier... Ivanti released a patch for this vulnerability on February 11, 2025.
4 indicators attributed to this actor: domains, IPs, hashes, and other artifacts pulled from reporting. View more in app.
7 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
UNC5337 is a China-nexus threat actor known for exploiting edge-appliance vulnerabilities (notably Ivanti Connect Secure CVE-2025-0282/0283) to gain access to networks, leading to operational downtime and requiring extensive remediation.
China-nexus cyber espionage activity exploiting Ivanti Connect Secure (ICS) CVE-2025-0282 (as a zero-day) to deploy the SPAWN malware ecosystem and related tooling (DRYHOOK, PHASEJAM).
China-linked cyber espionage activity targeting Ivanti Connect Secure VPN appliances by exploiting critical stack buffer overflow vulnerabilities to gain remote code execution and deploy the SPAWN* malware toolkits (e.g., SPAWNCHIMERA modules) for persistence, tunneling, backdoor access, and log wiping.
China-nexus activity cluster linked to some campaigns exploiting CVE-2025-0282 in Ivanti Connect Secure VPN appliances. The article describes exploitation observed since December 2024, but does not attribute every campaign, malware family, or post-exploitation activity to UNC5337.
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.