Malicious PDF — malware analysis report

Static analysis result for SHA-256 d4923b17b4513e87…

MALICIOUS

PDF

118.7 KB
MD5: 34d649b2187e1b99e36e352c68b5ad29 SHA-1: 657c8f7267258954ecb9899e5aaee8efa710b4f2 SHA-256: d4923b17b4513e873bb02ec2051f897a8d0d5fa0d0d8eef5d8b45d733632b8ca
166 Risk Score

Malware Insights

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

The PDF file contains embedded JavaScript that utilizes eval() and String.fromCharCode, indicating an attempt to obfuscate malicious code. Heuristics suggest this JavaScript acts as a stager, likely downloading and executing a second-stage payload. The ClamAV detection 'Pdf.Exploit.Agent-36086' further confirms its malicious nature, pointing towards a known exploit pattern within PDF documents.

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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0006_000.js
f77d8d921a62e5e0067e136e60cc3d49f5535adc89341e960af5d0d4c460226f
pdf-javascript-stream PDF /JS object 6 at offset 0x143 627205 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).
legacy_pdfkit_stage_000.js
d36f95e2b93b8d454a204f3cbdc47eb847fcf4d3d5e6d33b0081674e94eb1773
deobfuscated-js double percent-decoded annotation JavaScript at offset 0x143 262144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 556 long base64-like blob(s).