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CL-UNK-1037 is Palo Alto Networks Unit 42’s tracking moniker for activity dubbed “Operation Rewrite,” operating in the broader BadIIS/SEO-poisoning ecosystem targeting IIS web servers. The activity involves compromising IIS instances and deploying mechanisms to intercept HTTP traffic and selectively inject or redirect users to gambling/scam content, using cloaking such as serving different content to crawlers vs. browsers and triggering redirects based on the presence of search-engine referrers. Unit 42 reports CL-UNK-1037 can implement this objective via multiple server-side approaches including native IIS modules, ASP.NET handlers, managed .NET IIS modules, and a PHP front-controller rewrite model. Unit 42 assesses CL-UNK-1037 as a high-confidence Chinese-speaking operator based on linguistic and infrastructure artifacts. Unit 42 also reports a moderate-confidence link to ESET “Group 9” based on design and direct C2 domain-family overlap (e.g., 008php/yyphw/300bt subdomain families), and a low-confidence connection to Talos’ DragonRank based on similarity without infrastructure overlap. Known alias: Operation Rewrite.
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1 distinct technique observed across reporting, grouped by tactic. Hover any cell for the evidence excerpt; click through for MITRE's full description.
1 malware family attributed to this actor across reporting.
2 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Likely Chinese-speaking cluster conducting SEO poisoning (Operation Rewrite) to redirect traffic and plant web shells (BadIIS).
Adjacent IIS SEO-poisoning cluster that can implement the same objective via multiple web-stack mechanisms (native IIS modules, ASP.NET handlers, managed .NET IIS modules, and PHP front-controller 'rewrite' model); discussed as ecosystem-adjacent to UAT-8099/WEBJACK rather than a proven alias.
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.