Malicious PDF — malware analysis report

Static analysis result for SHA-256 a6ad36061547865a…

MALICIOUS

PDF

118.7 KB
MD5: b4d4ca1005b33dca387d74a9cc6fd694 SHA-1: f1837c10976480d8c8eaa955e7f5a5d1f03b6a2e SHA-256: a6ad36061547865a7f7c62ae72714b077cfd96aa067eb18afd10e8e5bee4ce70
166 Risk Score

Malware Insights

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

The PDF contains embedded JavaScript that utilizes eval() and String.fromCharCode, indicating an attempt to obfuscate malicious code. High-confidence heuristics like 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_EVAL' confirm the presence and execution of JavaScript. The 'PDF_JS_LARGE_COMMENT_PADDED_EVAL' heuristic specifically points to a stager pattern. ClamAV detection as 'Pdf.Exploit.Agent-36086' further solidifies the malicious nature. The primary attack vector appears to be exploiting a PDF vulnerability to download and execute a secondary payload.

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
95388d6df95e5c7c895b1e6e415d83c0b7486ee181f79f5ddbd99627eda1491a
pdf-javascript-stream PDF /JS object 6 at offset 0x143 626822 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).