UAT-8099: Chinese-speaking cybercrime group targets high-value IIS for SEO
fraud
blog.talosintelligence.com/uat-8099-…
In April 2025, Cisco Talos identified a Chinese-speaking cybercrime group,
tracked as UAT-8099, which targets a broad range of vulnerable IIS servers
across specific regions. This group focuses on high-value IIS servers that
have a good reputation within these areas to manipulate search engine results
for financial gain.
UAT-8099 operates as a cybercrime group conducting SEO fraud. Additionally,
UAT-8099 uses Remote Desktop Protocol (RDP) to access IIS servers and search
for valuable data such as logs, credentials, configuration files and sensitive
certificates, which they package for possible resale or further exploitation.
Upon discovering a vulnerability in a target server, the group uploads a web
shell to collect system information and conduct reconnaissance on the host
network. They then enable the guest account, escalate its privileges to
administrator level, and use this account to enable RDP. For persistence, they
combine RDP access with SoftEther VPN, EasyTier (a decentralized virtual
private network tool) and FRP reverse proxy tool. Subsequently, the group
performs further privilege escalation using shared tools to gain system-level
permissions and install BadIIS malware. To secure their foothold, they deploy
defense mechanisms to prevent other threat actors from compromising the same
server or disrupting their setup.
This blog post provides a comprehensive overview of the campaign’s
victimology, including the regions affected and the potential consequences of
BadIIS infections. It also details the attack chain, automation scripts
employed, and the malware and shared hacking tools UAT-8099 commonly uses.