Malicious PDF — malware analysis report

Static analysis result for SHA-256 73bc2a7503b3e293…

MALICIOUS

PDF

8.1 KB Created: 2008-31-20 53:85:00 Authoring application: Scribus 1.3.3.12 (via Scribus PDF Library 1.3.3.12)
MD5: 35912f4f6c10bded9da117d14f2c3d80 SHA-1: 5418193807c2626821ed766202ad941e81e6d2df SHA-256: 73bc2a7503b3e2938ab26a94a3f98ef5c6390eafb121e7091b1784f465c376a2
310 Risk Score

Malware Insights

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

The PDF file contains embedded JavaScript that utilizes eval() and unescape() functions, indicating an attempt to obfuscate malicious code. The script is designed to download and execute a second-stage payload from the provided URLs, specifically targeting a known PDF exploit cluster. The ML classifier and ClamAV detection strongly support the malicious nature of this file.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 9

  • PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER
    PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
  • ClamAV: Pdf.Exploit.Agent-35587 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-35587
  • 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.
  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution
  • unescape() call high PDF_UNESCAPE
    unescape() found — often used to decode shellcode in PDF JS exploits
  • 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://max.gunggo.com/show_ad.ashx?type=pop&sid=2373&cid=2590&cm=1&fc=4&hr=24&cb=
    • http://ads.doclix.com/adserver/serve/js/doclix_synd_overlay.js
    • http://max.gunggo.com/show_ad.ashx?type=pop&sid=2373&cid=2590&cm=1&fc=4&hr=24&cb='+cache_buster+

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0013_001.js
672d128a972cb223eb07fc01ed1065c302a8e929128f3e3b6f4df8b3498fe2b5		 pdf-javascript-stream PDF /JS object 13 at offset 0x3D9 5778 bytes
Detection
ClamAV: Pdf.Exploit.Agent-35587
Obfuscation or payload: likely
Carved artifact contains 5 eval/decoder/string-building token(s).
javascript_obj0013_002.js
b2b7c1818289e390458403bf5e3bddedca323f44b0fd25138775caffd97f411a		 pdf-javascript-stream PDF /JS object 13 at offset 0x3FF 7264 bytes
Detection
ClamAV: Pdf.Exploit.Agent-35587
Obfuscation or payload: likely
Carved artifact contains 6 eval/decoder/string-building token(s).

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