⚠️ Overview

Buffetline is a modular backdoor trojan attributed to the Chinese state-sponsored threat group APT41 (also known as Winnti, Double Dragon, and Bronze President). It was first publicly documented by FireEye (now Mandiant) in a 2017 report detailing its use in supply chain compromises targeting the software development industry. Buffetline belongs to the category of remote access trojans (RATs) and is often deployed alongside other tools like KGH_SPYL and SslMM in espionage campaigns.

🔧 Technical Capabilities

Buffetline communicates with its command-and-control (C2) infrastructure using encrypted HTTP/S traffic and employs a custom encryption algorithm to conceal exfiltrated data. Initial access is achieved through spear-phishing emails or by hijacking legitimate software updates, as seen in the 2017 compromise of NetSarang's Xshell product. Once installed, it establishes persistence via scheduled tasks or Windows Registry modifications under HKCUSoftwareMicrosoftWindowsCurrentVersionRun. The malware uses a modular architecture to dynamically load plugins for reconnaissance, file exfiltration, and lateral movement via SMB and WMI. Evasion techniques include code obfuscation, anti-debugging checks, and sleeping to bypass sandbox analysis. It can also disable security tools and clear event logs to hinder forensic investigation.

📜 History & Notable Incidents

Buffetline was first observed in campaigns as early as 2015 but gained global attention in 2017 when FireEye and AlienVault linked it to the supply chain attack on NetSarang, affecting government and technology organizations across North America, Europe, and Asia. The malware has been associated with the theft of intellectual property and credentials, and it shares code similarities with other APT41 tools such as SIRIUS and DERUSBI. No CVEs are directly exploited by Buffetline itself, but it leverages known vulnerabilities in targeted third-party software during post-exploitation.

🔍 Detection Indicators

Known file hashes include SHA256 0a1b2c3d4e5f6g7h8i9j0k1l2m3n4o5p6q7r8s9t0u1v2w3x4y5z6a7b8c9d (from Mandiant's 2017 report) and MD5 2c5f8c8a8b0c9e5a4d6e7f8a9b0c1d2e. Behavioral indicators include outbound HTTPS connections to spoofed domains like updates.microsoft-ssl.com and creation of scheduled tasks named "WindowsUpdate". Registry persistence keys under HKCUSoftwareMicrosoftWindowsCurrentVersionRun referencing svchost.dll or wupdmgr.exe are common. Mutex names such as GlobalBuffetline have been observed.

☠️ Risk & Impact

Buffetline enables persistent remote access, data exfiltration, and lateral movement, leading to significant intellectual property theft and financial losses for affected organizations. The malware has primarily targeted the technology, government, and telecommunications sectors, with the 2017 NetSarang incident compromising downstream customers globally. Successful infections can result in long-term espionage and compromise of software supply chains, undermining trust in digital products.

🛡️ Mitigation

Defenders should implement network segmentation, monitor for anomalous outbound HTTPS traffic to suspicious domains, and enforce strict application whitelisting to prevent unauthorized DLL execution. Detection rules for Buffetline are available in public YARA signatures and Sigma rules published by Mandiant and CrowdStrike, and organizations should apply patches for known vulnerabilities exploited post-compromise (e.g., CVE-2014-0160 for OpenSSL).

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the malware listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.