Malicious PDF — malware analysis report

Static analysis result for SHA-256 9b1b04635e164b51…

MALICIOUS

PDF

3.8 KB
MD5: df397bf8b07781e2a2e95b4f37f1b244 SHA-1: 77eb254dcfdefb55abbf92b6fb61a0b0a2f967c3 SHA-256: 9b1b04635e164b514d39ce84d9beb399f739bbc3a474d174391ddd3c786ea9af
142 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File

The file is identified as malicious by ClamAV with the signature Pdf.Exploit.Agent-36178. Static analysis reveals the presence of embedded JavaScript, utilizing String.fromCharCode and various decoding filters (ASCIIHexDecode, ASCII85Decode), which are common techniques for obfuscating malicious code within PDFs. The ML classifier also strongly indicates maliciousness. The primary attack vector appears to be exploiting a PDF vulnerability to run JavaScript, which is likely responsible for downloading and executing a further stage of malware.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 6

  • ClamAV: Pdf.Exploit.Agent-36178 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36178
  • ASCIIHexDecode filter (with exploit indicators) medium PDF_FILTER_HEX
    Hex-encoding filter present alongside exploit delivery indicators — often used to hide payload or shellcode bytes
  • JavaScript action low PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • String.fromCharCode low PDF_FROMCHARCODE
    String.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules. (matched inside decoded stream)
  • ASCII85Decode filter (with exploit indicators) low PDF_FILTER_85
    ASCII85 encoding filter present alongside exploit delivery indicators — uncommon outside of obfuscation