⚠️ Overview

PS1Bot is a PowerShell-based botnet malware first documented by Fortinet in February 2017, primarily designed for credential harvesting, distributed denial-of-service (DDoS) attacks, and cryptocurrency mining. It is attributed to Chinese-speaking threat actors and falls under the categories of botnet, infostealer, and cryptojacker.

🔧 Technical Capabilities

PS1Bot propagates via phishing emails containing malicious PowerShell scripts and exploits SMB vulnerabilities (e.g., EternalBlue, MS17-010) for lateral movement. Its command-and-control (C2) infrastructure uses HTTP/HTTPS with encrypted payloads, often hosted on compromised WordPress sites or cloud services. The malware establishes persistence through scheduled tasks and registry run keys (e.g., HKCUSoftwareMicrosoftWindowsCurrentVersionRun). Evasion techniques include obfuscated PowerShell code, disabling Windows Defender via registry modification, and checking for sandbox environments before execution. It can download secondary payloads, execute arbitrary commands, and exfiltrate browser-stored credentials using .NET libraries.

📜 History & Notable Incidents

First observed in 2017 targeting Asian organizations, PS1Bot resurfaced in 2020 campaigns against healthcare and manufacturing sectors. No specific CVEs are directly tied to the malware; however, it often leverages CVE-2017-0144 (EternalBlue) for propagation. In 2021, security researchers identified a variant using Telegram bots for C2 communication. No major law enforcement actions have been reported.

🔍 Detection Indicators

Known file hashes include SHA256 e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 (sample variant). Behavioral indicators include base64-encoded PowerShell commands in event logs (Event ID 4104), outbound connections to suspicious IP ranges, and creation of mutex named GlobalPS1Mutex. User-Agent strings typical of PS1Bot contain Mozilla/5.0 (Windows NT 6.1; Trident/7.0; rv:11.0) for HTTP C2 traffic.

☠️ Risk & Impact

PS1Bot primarily exfiltrates credentials and system information, enabling lateral movement and data theft. It can also mine Monero cryptocurrency, causing performance degradation and increased electricity costs. Sectors most affected include healthcare, manufacturing, and education, with financial losses stemming from ransom demands, system downtime, and remediation efforts.

🛡️ Mitigation

Defenders should block PowerShell execution from untrusted sources, apply patches for EternalBlue (MS17-010), and implement network segmentation. Detection can be enhanced using YARA rules (e.g., rule PS1Bot_Phishing) and monitoring for Event ID 4104 with suspicious base64 strings. Endpoint detection tools and application whitelisting are recommended to prevent initial execution.

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