Malicious PDF — malware analysis report

Static analysis result for SHA-256 f6571c9d592014bb…

MALICIOUS

PDF

118.4 KB
MD5: 0ec4651c85a1f1f5a1b016eff88dbdeb SHA-1: 8672da6b21b03c85c08d7fe0ef2144829bd8d348 SHA-256: f6571c9d592014bb8c8a6bf4e244322c59d60dafbe5eef077a37641fa1ce19c8
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File T1566.002 Spearphishing Attachment

The file is a PDF containing embedded JavaScript, as indicated by multiple heuristic firings including PDF_JAVASCRIPT, PDF_JS, and PDF_EVAL. The critical ClamAV detection of 'Pdf.Exploit.Agent-36086' strongly suggests it's a known exploit. The presence of a large, padded JavaScript eval stager points to a sophisticated obfuscation technique commonly used to hide malicious code. The JavaScript stream, identified as 'javascript_obj0006_000.js', is likely responsible for executing the exploit and downloading a secondary payload, although its exact function is obscured.

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
d8cbe14ec5ca8a1a6e33a9908e0834e0325cf7da4364cda8cb1cd8441bbfb31e
pdf-javascript-stream PDF /JS object 6 at offset 0x143 626148 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).