Malicious PDF — malware analysis report

Static analysis result for SHA-256 4f782c950eab051a…

MALICIOUS

PDF

118.6 KB
MD5: fc5e61422256c6423e97d89eb9537d7c SHA-1: ebca8d554f61d8f96004481d08335c6ebe4a30c5 SHA-256: 4f782c950eab051aa36e2fd0f7f5d9cef51aca36bfcb3850e7b5c158bc5dcf2e
196 Risk Score

Malware Insights

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

The PDF contains embedded JavaScript, including a call to eval() within a padded comment, a common stager technique. ClamAV identifies this as 'Pdf.Exploit.Agent-36086'. The ML classifier also strongly indicates maliciousness. The embedded JavaScript is likely responsible for downloading and executing a second-stage payload, as suggested by the heuristic 'PDF_JAVASCRIPT' and the presence of an extracted JavaScript file.

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
6ab58a24fd0681ef7bc78e78d280e0e2577ee6de6ff22469bfbe83b3de1cb4f0
pdf-javascript-stream PDF /JS object 6 at offset 0x143 626691 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).