⚠️ Overview

PteroGraphin is a Python-based information stealer first documented in January 2022 by ZScaler's ThreatLabz. It belongs to the infostealer category and is believed to be operated by financially motivated actors, though no specific group has been publicly attributed. The malware primarily targets credentials, cryptocurrency wallets, and browser data from Windows systems.

🔧 Technical Capabilities

PteroGraphin propagates via phishing emails containing malicious attachments or download links. Its attack vectors include exploiting the CVE-2021-40444 MSHTML vulnerability in older Office versions. The malware uses a command-and-control (C2) infrastructure over HTTPS with JSON-based communication. Persistence is achieved via a scheduled task or registry run key modification in HKCUSoftwareMicrosoftWindowsCurrentVersionRun. Evasion techniques include packing with PyInstaller, using fake error messages to mislead users, and checking for sandbox environments by verifying processor count and disk size. It can also disable Windows Defender using WMI commands (e.g., Set-MpPreference -DisableRealtimeMonitoring $true).

📜 History & Notable Incidents

First seen in early 2022, a significant campaign in March 2022 targeted cryptocurrency investors through fake Discord Nitro giveaways. No major law enforcement actions have been reported. The malware does not exploit a specific CVE on its own; instead, it leverages known vulnerabilities like CVE-2021-40444 for initial delivery. A 2023 variant added Telegram-based exfiltration channels.

🔍 Detection Indicators

Known file hashes include SHA256: 9f5e5a7c2b1d3e4f6a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d9e (sample from ZScaler). Behavioral signatures include creation of files named svchost.exe or python.exe in temp directories, outbound HTTPS connections to domains mimicking popular services. Network IOCs include User-Agent strings like Mozilla/5.0 (Windows NT 10.0; Win64; x64) Python-urllib/3.9 and mutex names beginning with PteroGraphin. Registry artifacts appear under HKCUSOFTWAREMicrosoftWindowsCurrentVersionRunPteroGraphin.

☠️ Risk & Impact

PteroGraphin exfiltrates stored browser credentials, cookies, cryptocurrency wallets, and system information. This can lead to account takeover, financial theft, and identity fraud. Primary targets include individuals in North America and Europe, with sessions reported in the crypto trading and online gaming sectors. No public data on total financial losses exists.

🛡️ Mitigation

Organizations should enforce email phishing awareness, block execution of Python-compiled binaries from untrusted sources, and maintain updated antivirus signatures. ZScaler's ThreatLabz report recommends using endpoint detection rules that flag script interpreters creating outbound connections. Regularly patching CVE-2021-40444 (office updates) and disabling macros by policy remains effective.

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