Malicious PDF — malware analysis report

Static analysis result for SHA-256 3d6f8b1a3b19d298…

MALICIOUS

PDF

15.8 KB
MD5: fff967685bf9f8db740a6920705c9e05 SHA-1: 63e1d196d55f2ec42536e4eed4738b61854fd780 SHA-256: 3d6f8b1a3b19d298f8cd4793b5941407694b5f7b68f5667dbd32fe892654bf53
196 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 JavaScript/JScript T1204.002 Malicious File

The PDF contains embedded JavaScript, including a call to eval() and a large comment-padded eval stager, which is a common technique for obfuscating malicious code. ML classifiers and ClamAV also flagged this file as malicious, specifically identifying it as 'Pdf.Exploit.Agent-36086'. The embedded JavaScript is likely responsible for downloading and executing a secondary payload, as indicated by the heuristic firings and the ML classification.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 7

  • ClamAV: Pdf.Exploit.Agent-36086 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36086
  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • Large comment-padded JavaScript eval stager high PDF_JS_LARGE_COMMENT_PADDED_EVAL
    PDF JavaScript contains a very large stream padded with long random-looking block comments around String.fromCharCode and eval. This is an exploit-kit obfuscation shape used to bury a decoder and recovered stage inside noise, not normal PDF form automation.
  • 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)
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0006_000.js
d9dba7b8dbdeabdb798e62708a02a77d048f1830b6c59237e3d32d7cc878691f
pdf-javascript-stream PDF /JS object 6 at offset 0x143 426870 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 42 long base64-like blob(s).