Malicious PDF — malware analysis report

Static analysis result for SHA-256 ef8e4d2399a470a6…

MALICIOUS

PDF

3.4 KB First seen: 2026-05-10
MD5: 3e78f7300dc4586ee23e1bf20a9d2db5 SHA-1: 5c14f7a7db9f979c82cac6cd7c06bd8784571d82 SHA-256: ef8e4d2399a470a68843f0acf0f91b64e5a81301a573b7983df013cdf7661ca2
118 Risk Score

Malware Insights

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

The PDF contains JavaScript actions and uses ASCIIHexDecode filters, which are common indicators of malicious PDFs. The ML classifier strongly flags this file as malicious. The presence of JavaScript suggests an attempt to download and execute a secondary payload, a common technique for initial access.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 3

  • JavaScript action low 1 related finding PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • PDF JavaScript rebuilds a builtin via replace() to run a char-code array critical PDF_JS_REPLACE_OBFUSCATED_CHARCODE_BUILDER
    Decoded PDF JavaScript resolves a String builtin from a junked literal — e.g. String['eQvoaol3'.replace(/[3oQS5]/g,'')] yielding fromCharCode/eval — and feeds a large numeric char-code array through it to rebuild and execute the next stage. Dynamically reconstructing a builtin name by stripping junk characters has no benign purpose; paired with the char-code payload array it is an unambiguous obfuscated-JavaScript exploit dropper.
  • 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