LLMShare malvertising campaign: attackers embed fake outage pages in ChatGPT share links and serve infostealer downloads via Google Ads

Push Security documented LLMShare, a malvertising campaign in which attackers buy Google Ads targeting "ChatGPT" and "ChatGPT download" queries (Push Security, 2026-05-29; BleepingComputer, 2026-05-29). Victims clicking the ads land on legitimate chatgpt.com/s/[unique-id] share URLs that render attacker-controlled HTML — a fake high-traffic outage page with a "Download our desktop app to continue" button — directly from the OpenAI domain. Because chatgpt.com is trusted by enterprise web-filtering rules and firewalls, the landing page is not blocked. The download button redirects to an attacker-controlled domain impersonating OpenAI; the site uses cloaking (serves a benign page to scanners). Windows users receive an infostealer payload. The technique exploits the same ChatGPT Artifacts/sharing feature previously abused in the ACR Stealer campaign (covered 2026-05-26) and extends it to malvertising. Detection: monitor for browser-spawned executable downloads from chatgpt.com domains — legitimate ChatGPT desktop app downloads do not originate from that path; alert on unusual process launch from browser-extracted or browser-downloaded unsigned executables. MITRE ATT&CK: T1566.002, T1204.001, T1036, T1027.