Malicious PDF — malware analysis report

Static analysis result for SHA-256 66625bf32416c706…

MALICIOUS

PDF

45.0 KB
MD5: 346d52512cc62d870a4b84f5d7249aaf SHA-1: a1f007864311afcd43866e6ac9c7cb6b5fce2337 SHA-256: 66625bf32416c70603456f9ea450ce78c7088dc1f905abb8c12c56be284ef128
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is a PDF file flagged as malicious by ClamAV and an ML classifier. Embedded JavaScript streams were detected, and the ClamAV signature 'Pdf.Exploit.Agent-36128' suggests exploitation of a PDF vulnerability. The JavaScript appears to be heavily obfuscated but is designed to execute code, likely to download and run a second-stage payload.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9999

Heuristics 4

  • ClamAV: Pdf.Exploit.Agent-36128 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36128
  • 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.
  • 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.

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0008_000.js
40f8da3b3934bdb66ae04c2802b642b26ce4a1f86351a86cd511097e26d10489		 pdf-javascript-stream PDF /JS object 8 at offset 0x1E7 45305 bytes
javascript_obj0008_001.js
519b7354a3ba7298bd99bab0efdc292465150922bad59b0c1a74684246fa34c8		 pdf-javascript-stream PDF /JS object 8 at offset 0x20A 45555 bytes
Detection
ClamAV: Pdf.Exploit.Agent-36128
Obfuscation or payload: unlikely
legacy_pdfkit_stage_000.js
b2681c2eb7054e8bc8ffd5c760969f6822963411a848abe414ec468e6971c764		 deobfuscated-js double percent-decoded annotation JavaScript at offset 0x1E7 33047 bytes

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