Malicious PDF — malware analysis report

Static analysis result for SHA-256 41a2f71c5a1f1df8…

MALICIOUS

PDF

118.6 KB
MD5: a6012d17844ddbb112e39c59d38f9c15 SHA-1: 39803e8b0a7c5e21831a1f6438bf9ea058a1808b SHA-256: 41a2f71c5a1f1df8972b1099617bf05c118fe039669f1ef3e37a9beeb4c9ab6a
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1059.007 JavaScript

The PDF contains embedded JavaScript, including a large comment-padded eval stager. The presence of `eval()` and `String.fromCharCode` indicates obfuscated code execution. ClamAV detection as 'Pdf.Exploit.Agent-36086' strongly suggests exploit activity. The primary function of the embedded JavaScript appears to be the download and execution of a second-stage payload, as indicated by the heuristic 'PDF_JS_LARGE_COMMENT_PADDED_EVAL'.

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
97339cf74902eb24942aed594e23dcfba3f3fbafc12cbc140b2db78531aa1120
pdf-javascript-stream PDF /JS object 6 at offset 0x143 627425 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).