Malicious PDF — malware analysis report

Static analysis result for SHA-256 b1966ef7c9ae234a…

MALICIOUS

PDF

29.3 KB
MD5: be1ea0ae0ab58582e256ee7822de4627 SHA-1: f65c954b3327d056e1400dbb6b0175371df8e122 SHA-256: b1966ef7c9ae234a727f9ae0bbec7b67f4d33b4c045cc160facd0366524497cf
304 Risk Score

Malware Insights

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

This PDF file was flagged as malicious by a machine learning classifier and ClamAV, which identified it as Pdf.Exploit.Agent-36098. Static analysis revealed embedded JavaScript and a Flash object (SWFNAME.swf), indicating a multi-stage attack. The embedded JavaScript, particularly the use of eval() and unescape() functions, suggests code obfuscation likely designed to download and execute further malicious content. The presence of these components points towards an exploit delivery mechanism.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 10

  • ClamAV: Pdf.Exploit.Agent-36098 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36098
  • ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV
    ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
  • RichMedia (Flash) high PDF_RICHMEDIA
    PDF contains /RichMedia (Adobe Flash) which is a historic exploit vector
  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • unescape() call high PDF_UNESCAPE
    unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
  • 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.
  • Embedded file low PDF_EMBEDDED
    PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload
  • 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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
SWFNAME.swf
a98024b4ee1377e872e3ebaf1c361600c270db5fd5ba79f256106c0c566dde29
pdf-embedded-file PDF EmbeddedFile object 16 at offset 0xC29 26777 bytes
Detection
ClamAV: Pdf.Exploit.Agent-35955
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.
javascript_obj0006_000.js
e1ab3bbf30605cecdce6db9d2556198626dbb178f7a4cb471a9436bb6e8bd92f
pdf-javascript-stream PDF /JS object 6 at offset 0x82D 462 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 3 eval/decoder/string-building token(s).
legacy_pdfkit_stage_000.js
c17918bf4425dae54ec926796e46af9ea18d1a262db6d9ca2094d39fe4834705
deobfuscated-js repeated-marker hex decoded JavaScript at offset 0x64 3464 bytes