Malicious PDF — malware analysis report

Static analysis result for SHA-256 4dfcebc34a24bdb0…

MALICIOUS

PDF

15.8 KB
MD5: f23784c2d07dbcdf81a8243e6aa5108f SHA-1: e2337256e72480291c14def505d5b89005355cda SHA-256: 4dfcebc34a24bdb0d8bccfbb616104dc2b504e7bb6bb9e9bcfcfcb9359e2bf04
196 Risk Score

Malware Insights

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

The PDF contains embedded JavaScript, including a large, comment-padded eval stager. This JavaScript is highly suspicious due to the use of eval() and String.fromCharCode, indicating obfuscation. The ML classifier and ClamAV detection strongly suggest malicious intent, likely to download and execute a second-stage payload. The specific ClamAV signature 'Pdf.Exploit.Agent-36086' points to a known exploit.

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
a5819068c54197b8ba17b30a55dc3b0eae53dc55189c999138ac6bba12b7acc0
pdf-javascript-stream PDF /JS object 6 at offset 0x143 425837 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).