UAT-8099 Chinese Cybercrime Group Uses BadIIS Malware for SEO Fraud and Credential Theft on IIS Servers

A Chinese-speaking cybercrime group, tracked as UAT-8099, has been identified targeting high-value Microsoft Internet Information Services (IIS) servers across multiple countries, including India, Thailand, Vietnam, Canada, and Brazil. The group’s primary objective is to conduct search engine optimization (SEO) fraud by manipulating search rankings through the compromise of reputable IIS servers. UAT-8099 leverages a variety of tools and techniques, including the deployment of BadIIS malware, web shells, open-source hacking utilities, and Cobalt Strike to maintain persistence and evade detection on compromised systems. The attackers use customized automation scripts to further obfuscate their activities and ensure continued access. Once inside a target server, the group exploits vulnerabilities to upload web shells, which are then used to collect sensitive information such as credentials, configuration files, logs, and certificate data. This stolen data is likely packaged for resale or used in further criminal operations. Cisco Talos researchers discovered several new BadIIS malware samples associated with this campaign, noting that some clusters had very low detection rates and others contained debug strings in simplified Chinese, indicating the group’s origin. The campaign has affected a diverse set of organizations, including universities, technology companies, and telecommunications providers, highlighting the group’s broad targeting strategy. UAT-8099’s operations are financially motivated, with a focus on monetizing both the manipulation of search engine results and the theft of valuable credentials. The group also utilizes Remote Desktop Protocol (RDP) to access and further exploit compromised IIS servers. The technical sophistication of the campaign is evident in the attackers’ ability to evade traditional security measures and maintain long-term persistence. The use of reputable, high-value servers for SEO fraud increases the impact of the campaign, as these servers are more likely to influence search engine rankings. The campaign demonstrates the ongoing threat posed by financially motivated cybercrime groups leveraging advanced malware and exploitation techniques. Security researchers recommend organizations running IIS servers implement robust monitoring, patch management, and incident response procedures to detect and mitigate such threats. The exposure of configuration files and certificates also raises concerns about potential follow-on attacks, including lateral movement and further credential abuse. The campaign’s discovery underscores the importance of threat intelligence sharing and proactive defense measures in protecting critical web infrastructure.