Malicious PDF — malware analysis report

Static analysis result for SHA-256 b42baaeabfd78d4a…

MALICIOUS

PDF

5.4 KB Created: 1469-57-02 55:75:16 -18:30 Authoring application: Acrobat Editor 8.0 (via Adobe Acrobat 8.1.0)
MD5: f98c48185649f002b5d6f40422f8273f SHA-1: 5165a30bc0a302a845c9c491b762fb217a9490d0 SHA-256: b42baaeabfd78d4a164b38f65fbd8b83142455f949885de74dd74c3f46f6014a
246 Risk Score

Malware Insights

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

The PDF file contains embedded JavaScript that utilizes the util.printf function, indicating an exploitation attempt targeting CVE-2008-2992. The JavaScript is heavily obfuscated and appears to decode further layers, ultimately aiming to execute arbitrary code. This is further supported by ClamAV detections of 'Pdf.Exploit.Agent-35551'. The primary goal is likely to download and execute a second-stage payload.

Heuristics 9

  • util.printf — CVE-2008-2992 critical CVE exact CVE_2008_2992
    PDF JavaScript calls util.printf() — CVE-2008-2992 is a stack buffer overflow in Adobe Reader triggered by a long format-specifier argument. Widely exploited in the wild after disclosure. (identified after JavaScript deobfuscation)
  • ClamAV: Pdf.Exploit.Agent-35551 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-35551
  • 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 (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.
  • 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.
  • 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/
    • http://ns.adobe.com/pdf/1.3/

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0028_000.js
8d11a67a73619d3f54616e0d62cf9c6bf83fae658491206497ef577f89651a58		 pdf-javascript-stream PDF /JS object 28 at offset 0x4E5 3563 bytes
Detection
ClamAV: Pdf.Exploit.Agent-35551
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
custom_b64_stage_000.js
c37446edfb101a4e7cc3f1603a96aa03738534174047309ee9fd9b2f296dc90c		 deobfuscated-js custom Base64 decoded JavaScript layer 1 (PDF /JS object 28) at offset 0x84B 2012 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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