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Hackers Target Claude, Cursor and Codex AI Agents to Steal Tokens and Prompt Histories
Gen Digital found infostealers like Amatera and Remus stealing AI coding agent tokens, prompt histories, and MCP configs from infected Windows and macOS machines.
Gen Digital analysts observed Amatera and Remus detections among tens of thousands of protected Windows users over three months, with Amatera targeting Cline and Continue data and Remus targeting Claude, Cursor, and OpenCode. CallbackBeaver added Cursor and Claude to its collection scope with more than 5,000 samples in 30 days, while macOS-focused Djinn Stealer has been associated with Claude, Codex, Gemini, Cline, OpenCode, and Kilo. The stealers harvest access and refresh tokens, prompt histories, and MCP configuration files that can expose source control, ticketing, databases, cloud resources, and sensitive project context for follow-on fraud. Many stealers add targets via remotely managed rules, meaning this is an adaptation of existing infostealers rather than a new vulnerability in the AI tools themselves.
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Week in review: AiTM phishing kit used to hijack AWS accounts, year-long malware campaign targets HR
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Infostealers Target Claude, Cursor, Codex and Other AI Agents to Steal Credentials and Sensitive Data
Gen Digital researchers report infostealer families Amatera, Remus and CallbackBeaver now harvest Claude, Cursor and Codex agent data, including tokens and MCP configs.
Gen Digital researchers found commodity infostealers extending their collection rules to local AI coding agent data from Claude, Cursor, Codex, Cline, Continue and OpenCode on Windows and macOS. Amatera targets Cline and Continue, Remus targets Claude, Cursor and OpenCode, and CallbackBeaver added Claude and Cursor with more than 5,000 samples observed in 30 days; Djinn Stealer hits Claude, Codex, Gemini, Cline, OpenCode and Kilo on macOS. Stolen data includes access and refresh tokens, prompt histories, conversation databases and MCP configurations holding API keys, potentially exposing connected source-control, cloud and ticketing systems. Remus is assessed as a Lumma Stealer variant using EtherHiding C2 resolution via Ethereum smart contracts.
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Open VSX Removes 77 Malicious Evil Twin Extensions Exfiltrating Developer Data
77 malicious 'evil twin' Open VSX extensions impersonated developer tools and exfiltrated hostnames and detailed workspace reconnaissance to mangorbit.com.
Manifold Security found 77 extensions uploaded to the Open VSX marketplace between July 26 and August 1, 2026 that impersonate real Microsoft VS Code Marketplace tools, with all 77 sending data to mangorbit.com. 58 lightweight variants exfiltrate the hostname, while 19 recon variants collect editor details, OS username, Git remote hosts, CI environment variables (GitHub, GitLab, Azure DevOps, Buildkite, CircleCI, Codespaces, Gitpod), and installed extension IDs. The recon variant retries for up to seven days and can fall back to a DNS TXT record for exfiltration if the primary domain is blocked. The extensions were removed from Open VSX by August 3, 2026; the disclosure follows a separate npm supply chain campaign, ChainDrop, which compromised 450 packages with a Shai-Hulud worm variant.
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New Agent Tesla Malware Variant Boosts Evasion Capabilities
KnowBe4 documented an Agent Tesla v4 campaign using emoji-based code obfuscation to evade detection.
KnowBe4 researchers reported a campaign distributing Agent Tesla v4, a long-running Windows keylogger and infostealer. The new variant uses emoji-based code obfuscation, a novel technique, to hinder static analysis and evade security tooling. Defenders should watch for behavioral indicators such as credential theft and unusual process activity.
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