Malicious PDF — malware analysis report

Static analysis result for SHA-256 efdbe97d3b9bfc2d…

MALICIOUS

PDF

174.0 KB Created: 2009-08-07 15:58:01 +08:00
MD5: 6c134e7c9cf11c7bb14887ec5cdccce3 SHA-1: 5a6900bb4643586e1a912f249d5effe82a8a368e SHA-256: efdbe97d3b9bfc2d8f295072b485b832d5e1575568af3d4109b3ff0d6120c7c5
74 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1140 Deobfuscate/Decode Files or Information

The PDF file contains an embedded JavaScript stream which is heavily obfuscated and uses eval() and String.fromCharCode() functions. This script is likely responsible for downloading and executing a second-stage payload. Due to the obfuscation, the exact nature of the payload and its destination could not be determined with high confidence. The embedded artifact 'stream_004_off00000674.js' is the primary indicator of malicious activity.

Heuristics 7

  • 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. (matched inside decoded stream)
  • 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. (matched inside decoded stream)
  • Embedded file low PDF_EMBEDDED
    PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload (matched inside decoded stream)
  • 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
stream_004_off00000674.js
f52645fd5e5ae67990ca01ef67c88b1cc7b0adb3d9923f3a35020e29908e2f55		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x674 3658 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
objstm_0026_00.bin
6d922c74a8f96fada2b2823af27b994c895d4247ec51b574e434931b75030325		 pdf-objstm-decoded PDF /ObjStm 26 0 obj (inflated) 306 bytes

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