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UNC2643 is a preliminary intrusion cluster tracked by Mandiant during the early 2021 exploitation of on-premises Microsoft Exchange Server vulnerabilities collectively associated with ProxyLogon. It is one of several clusters identified during widespread exploitation activity that involved chaining CVE-2021-26855 with additional Exchange flaws to achieve remote code execution and deploy web shells on vulnerable Exchange Server 2013, 2016, and 2019 systems. Activity associated with this cluster falls within the broader wave of Exchange exploitation that included persistent web shell installation, execution under highly privileged Exchange-related processes, and follow-on post-compromise actions. Observed behaviors across the tracked clusters included reconnaissance, credential gathering, lateral movement, and additional compromise after initial access. Mandiant also documented web shell functionality designed to identify endpoint security products, indicating defensive awareness and defense-evasion considerations during post-exploitation. UNC2643 was tracked as a cluster rather than a fully resolved actor identity. In the same reporting period, Microsoft linked early exploitation of the ProxyLogon chain to the China-linked state-sponsored actor HAFNIUM, but the available information does not independently establish UNC2643 itself as a distinct named nation-state group beyond its role as one of Mandiant's preliminary Exchange exploitation clusters.
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.
4 distinct techniques observed across reporting, grouped by tactic. Hover any cell for the evidence excerpt; click through for MITRE's full description.
4 CVEs this actor has used in observed campaigns. 4 of them exploited in the wild.
CVE-2021-26855 (CVSS 9.1) is a server-side request forgery (SSRF) vulnerability in Exchange that allows the attacker to send arbitrary HTTP requests and authenticate as the Exchange server.
CVE-2021-26857 (CVSS 7.8) is an insecure deserialization vulnerability in the Unified Messaging service. Exploiting this vulnerability gives the threat actor the ability to run code as SYSTEM on the Exchange server.
CVE-2021-26858 (CVSS 7.8) is a post-authentication arbitrary file write vulnerability in Exchange. If the threat actor first authenticates with the Exchange server they could then use this vulnerability to write a file to any path on the server.
CVE-2021-27065 (CVSS 7.8) is a post-authentication arbitrary file write vulnerability in Exchange. If the threat actor first authenticates with the Exchange server they could then use this vulnerability to write a file to any path on the server.
2 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
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.