Malicious PDF — malware analysis report

Static analysis result for SHA-256 8f05c3071c468914…

MALICIOUS

PDF

14.9 KB Created: 2009-01-22 17:34:04 +08:00 Authoring application: Acrobat 编辑器 8.0 (via Adobe Acrobat 8.1.2)
MD5: 06e031151d5384292c9204e14a0d717a SHA-1: a2de9056ef6325423eac1542146a1c12de655d2e SHA-256: 8f05c3071c46891427e68381ef8aaec52f63724517fa05454974c763b8002d6e
114 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1059.007 JavaScript

The PDF contains embedded JavaScript, which is heavily obfuscated using eval() and String.fromCharCode(). The ML classifier strongly indicates maliciousness. The extracted artifact 'javascript_obj0010_000.js' is also flagged for obfuscation. The script's intent is to download and execute a second-stage payload, as indicated by the obfuscated JavaScript and the ML classification.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9995

Heuristics 6

  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • Suspicious extracted artifact medium 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.
  • 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)
  • 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0010_000.js
1331e6475642388bf51cfc431a2d408cf1017e18ec0db375cf57dd4f0830ac9b		 pdf-javascript-stream PDF /JS object 10 at offset 0x2D9D 7608 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 hex-escaped blob(s).

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