Hackers Exploit Claude Code Leak to Spread Vidar Infostealer and GhostSocks Malware
Cybercriminals are leveraging the recent accidental leak of Anthropic’s Claude Code source code to distribute malware via fake GitHub repositories. The incident began when an Anthropic employee inadvertently exposed the code, which was quickly archived and forked tens of thousands of times. Threat actors seized the opportunity, creating malicious repos under the username dbzoomh, falsely advertising "unlocked enterprise features" and unrestricted access.
Security firm Zscaler identified the fraudulent repositories, which appeared on the first page of Google search results for terms like "leaked Claude Code." The malicious payload a Rust-built executable named ClaudeCode_x64.exe deploys two threats: Vidar, a potent infostealer capable of harvesting browser data, passwords, and cryptocurrency wallets, and GhostSocks, a proxy malware that repurposes infected machines into residential proxies for malicious traffic routing.
The attackers continuously updated the malicious archive, suggesting evolving payloads, and experimented with different delivery methods, including a defunct "Download ZIP" button in a separate repo. GitHub has since removed the offending account, rendering the page inaccessible.
The incident adds to growing concerns over Anthropic’s security practices amid rapid product expansion. In recent weeks, researchers uncovered multiple vulnerabilities in Claude, including ShadowPrompt (March 27, 2026), a zero-click Chrome extension flaw enabling data exfiltration, and Cloudy Day (March 19, 2026), a three-vulnerability attack chain disclosed by Oasis. Despite fixes, Anthropic’s surging popularity has strained its infrastructure, prompting temporary usage throttling during peak demand.
Anthropic cybersecurity rating report: https://www.rankiteo.com/company/anthropicresearch
GitHub cybersecurity rating report: https://www.rankiteo.com/company/github
"id": "ANTGIT1775240707",
"linkid": "anthropicresearch, github",
"type": "Breach",
"date": "3/2026",
"severity": "85",
"impact": "4",
"explanation": "Attack with significant impact with customers data leaks"{'affected_entities': [{'customers_affected': 'Users downloading malicious '
'ClaudeCode_x64.exe',
'industry': 'Artificial Intelligence, Technology',
'name': 'Anthropic',
'type': 'Company'}],
'attack_vector': 'Fake GitHub repositories, malicious executables',
'customer_advisories': 'Users warned against downloading unofficial '
'Claude-related executables or repositories.',
'data_breach': {'data_exfiltration': 'Yes (via Vidar infostealer)',
'personally_identifiable_information': 'Yes',
'sensitivity_of_data': 'High',
'type_of_data_compromised': 'Browser data, passwords, '
'cryptocurrency wallets, '
'personally identifiable '
'information'},
'description': 'Cybercriminals leveraged the accidental leak of Anthropic’s '
'Claude Code source code to distribute malware via fake GitHub '
'repositories. The malicious payload, a Rust-built executable '
'named ClaudeCode_x64.exe, deployed Vidar infostealer and '
'GhostSocks proxy malware. The attackers created fraudulent '
'repos under the username dbzoomh, falsely advertising '
'unlocked enterprise features and unrestricted access.',
'impact': {'brand_reputation_impact': 'Growing concerns over Anthropic’s '
'security practices',
'data_compromised': 'Browser data, passwords, cryptocurrency '
'wallets',
'identity_theft_risk': 'High (due to Vidar infostealer)',
'operational_impact': 'Malicious traffic routing via infected '
'machines',
'payment_information_risk': 'High (due to Vidar infostealer)',
'systems_affected': 'Infected machines repurposed as residential '
'proxies'},
'initial_access_broker': {'entry_point': 'Fake GitHub repositories (dbzoomh)'},
'investigation_status': 'Ongoing (malicious repos removed, but payloads may '
'evolve)',
'lessons_learned': 'Need for stricter source code access controls, rapid '
'response to leaks, and enhanced monitoring of third-party '
'repositories.',
'motivation': 'Financial gain, data theft, proxy network establishment',
'post_incident_analysis': {'corrective_actions': 'Removal of malicious repos, '
'potential improvements in '
'code access controls and '
'employee training.',
'root_causes': 'Accidental source code leak by '
'Anthropic employee, rapid '
'exploitation by threat actors via '
'fake repositories.'},
'recommendations': 'Implement stricter access controls for sensitive code, '
'monitor for unauthorized forks/repositories, educate '
'employees on secure handling of proprietary code, and '
'enhance threat detection for malware distribution via '
'code leaks.',
'references': [{'source': 'Zscaler'}],
'response': {'containment_measures': 'GitHub removed the offending account '
'(dbzoomh)',
'third_party_assistance': 'Zscaler (security firm)'},
'title': 'Hackers Exploit Claude Code Leak to Spread Vidar Infostealer and '
'GhostSocks Malware',
'type': 'Malware Distribution',
'vulnerability_exploited': 'Accidental source code leak (Claude Code)'}