BadIIS Malware Spreads via SEO Poisoning in Operation Rewrite
In September 2025, cybersecurity analysts uncovered a targeted campaign in East and Southeast Asia, particularly Vietnam, orchestrated by a Chinese-speaking threat actor dubbed CL-UNK-1037. Using a custom malware named BadIIS, the group launched "Operation Rewrite" by employing SEO poisoning to direct unsuspecting users to compromised websites. These sites served as a launch point for deploying BadIIS, which stealthily redirected traffic, established persistent web shells, and enabled lateral movement within infected infrastructure. The attacks leveraged trusted search results to compromise both organizations and individuals, aiming to establish long-term footholds and facilitate future malicious operations. This incident highlights the increasing sophistication of adversaries leveraging advanced social engineering and technical tactics like SEO poisoning. The blending of supply chain and web application compromise with persistent malware demonstrates evolving TTPs that bypass conventional detection, emphasizing the urgent need for multilayered security and continuous vigilance for all organizations.
Kill Chain
