Malicious PDF — malware analysis report

Static analysis result for SHA-256 1b41e3f72db93a63…

MALICIOUS

PDF

22.8 KB Created: 2009-05-06 20:45:24 +08:00 Authoring application: DocuCom PDF Core Library
MD5: f3df19605806ffb79d88d206ec596eab SHA-1: 0ac728aa0e08aae4c04f30e51631d0487f996fab SHA-256: 1b41e3f72db93a63e0b5c9552761ea91039b519ae180bdf8ce923559491ef345
208 Risk Score

Malware Insights

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

The file is identified as a malicious PDF by ClamAV (Pdf.Exploit.Agent-35646) and a machine learning classifier. It contains embedded JavaScript streams, one of which uses the unescape() function, indicating an attempt to obfuscate malicious code. The primary function of the embedded scripts is to download and execute a second-stage payload, as suggested by the heuristic firings and the nature of PDF exploits.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9980

Heuristics 7

  • ClamAV: Pdf.Exploit.Agent-35646 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-35646
  • 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.
  • 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.
  • 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/xap/1.0/
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xap/1.0/mm/

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0003_000.js
3a63aa1468610780740c9dc83aeeec5b08cb097e75c7162b2fbf08d5be27c95c		 pdf-javascript-stream PDF /JS object 3 at offset 0x883 7299 bytes
Detection
ClamAV: Pdf.Exploit.Agent-35646
Obfuscation or payload: likely
Carved artifact contains 4 eval/decoder/string-building token(s).
javascript_obj0026_001.js
ca53d891511bf3d1978afe1a4259f2e95c19980a2209106508f51e2558a305a4		 pdf-javascript-stream PDF /JS object 26 at offset 0x20D6 14600 bytes
Detection
ClamAV: Pdf.Exploit.Agent-35646
Obfuscation or payload: unlikely

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