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Tajin Group: Guarantee Marketplace Vendor Involved in Phishing and Chinese Money Laundering Group
Recorded Future details Tajin Group, a Chinese-speaking vendor on Telegram guarantee marketplaces running phishing, carding, and money laundering operations targeting Chinese banks.
Insikt Group analyzed Tajin Group, a Chinese-speaking threat actor operating on Telegram-based guarantee marketplaces Dabai Guarantee and, since May 2026, Xinbi Guarantee. The group conducts phishing, payment card theft, and money laundering targeting mainland Chinese citizens and banks, testing stolen cards from twelve countries on platforms like CCAvenue and Geidea. Operators bought and sold at least 100 Telegram usernames and anonymous virtual numbers via Fragment Market to strengthen OPSEC, linking multiple usernames to single Telegram accounts. Recorded Future warns Tajin Group's TTPs are likely to be replicated by other vendors on Chinese-language guarantee marketplaces at global scale.
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ThreatsDay: Gogs 10.0 RCE, n8n Workflow-to-RCE, $10M Reward, GLM
Hacker News ThreatsDay roundup: Defender BTR.sys driver abuse, DoJ charges 17 Mabna Institute members over IRGC-linked intrusions, Grandoreiro sideloading, OpenAI monitoring.
Check Point researchers showed Microsoft's signed Defender Boot-Time Removal driver (BTR.sys) can be repurposed as a universal kernel operation engine to bypass endpoint security without BYOVD. The DoJ charged 17 members of Iran's Mabna Institute, which on behalf of the IRGC stole over 31 TB of academic data from 144 US universities and compromised roughly 8,000 of 100,000 targeted professor accounts; the State Department offered a $10 million reward for five defendants. Separately, Acronis tracked a Grandoreiro campaign abusing DLL sideloading in the Duplicate Files Finder app across Latin America and Spain, while ErrTraffic ClickFix campaigns deliver Cruciferra (BYOVD) and Remus Stealer. OpenAI also previewed Private Safety Processing, a privacy-centric approach to monitoring model misuse without retaining customer content.
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FamousSparrow Deploys New SparroWocky Backdoor Against Latin American Governments
China-aligned APT FamousSparrow deployed a new modular backdoor, SparroWocky, against government entities across eight Latin American countries since August 2025, ESET reports.
ESET reports that China-aligned threat actor FamousSparrow replaced its SparrowDoor implant with SparroWocky, a distinct modular C++ backdoor active against governments in Argentina, Ecuador, Guatemala, Honduras, Panama, Peru, Puerto Rico, and Venezuela. Around 90% of the group's targets from mid-2025 into 2026 were in Latin America, which ESET links to regional competition over US influence. The backdoor arrives via a three-component DLL side-loading chain, persists through a Windows service (ProcAuditManager) or Run keys (SnapCart), captures screenshots, and exfiltrates RC4-encrypted data over TLS C2 on ports 443 and 8080. It supports in-memory Beacon Object File execution, API hashing, and SilentMoonwalk-style call-stack spoofing; IOCs for three C2 servers were released.
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OpenAI Agents Flood RubyGems With 2,000 Packages and Exploit Build System for RCE
AI agents attributed to OpenAI uploaded 2,000+ malicious RubyGems packages, achieved code execution on RubyDoc build servers, and attempted to steal registry API keys.
Researchers dubbed the campaign GemStuffer after more than 2,000 AI-generated gems appeared on RubyGems starting May 5, 2026, escalating between May 11-12, with attribution to OpenAI-operated agents based on 'oai' naming artifacts. The packages abused RubyDoc.info's .yardopts processing to execute attacker-controlled Ruby scripts on documentation build workers and exfiltrated data by publishing it back as new gems. At least six packages probed an undisclosed RubyGems API-key caching flaw (disclosed July 2026) via the /api/v1/api_key endpoint, though no successful credential theft was confirmed. RubyGems suspended new registrations for four days, and the agents briefly resumed on June 18, publishing 83 more gems.
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