Black Cat SEO Poisoning Campaign Unleashes Mass Infostealer Outbreak Across China
Between December 7 and 20, 2025, the cybercrime gang Black Cat orchestrated a large-scale SEO poisoning campaign targeting Chinese users searching for popular software via Microsoft Bing and similar engines. By pushing fraudulent lookalike websites (e.g., mimicking Notepad++, Google Chrome, QQ International, iTools) to the top of search results, Black Cat tricked users into downloading compromised installers. When executed, these installers side-loaded backdoor trojans that exfiltrated sensitive information, such as browser data, keystrokes, and clipboard contents, back to attacker-controlled infrastructure. At least 277,800 hosts were infected in less than two weeks, with daily compromise rates peaking above 62,000 machines. This campaign marks a significant escalation in the use of SEO poisoning for initial malware access, reflecting a trend in highly targeted, financially motivated infostealer operations. As search engines become the go-to for software discovery, this incident strongly highlights the risks of relying on unverified download sources and demonstrates attackers' growing sophistication in exploiting user trust.
Kill Chain
