Malicious PDF — malware analysis report

Static analysis result for SHA-256 b6b1f07515eb8139…

MALICIOUS

PDF

174.9 KB Created: 2008-08-19 23:58:52 -08:00 Authoring application: Acrobat Editor 8.0 (via Adobe Acrobat 8.0)
MD5: bbfe7eec54e809171551ec7a61caf56b SHA-1: b51a64be7edbf9b6a27962e0952eddb937d3712c SHA-256: b6b1f07515eb81396b7ebff89ac17a0032568be0add433cf83b26720242f180d
148 Risk Score

Malware Insights

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

This PDF file contains embedded JavaScript, indicated by the PDF_JAVASCRIPT and PDF_JS heuristics. The PDF_EVAL and PDF_GENERIC_STAGE_RECOVERY heuristics suggest that the JavaScript is obfuscated and attempts to execute arbitrary code, likely to download and run a second-stage payload. The ML classifier also strongly indicates maliciousness. No specific family could be identified, and the embedded URLs were confirmed as benign.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9999

Heuristics 10

  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • Generic recovered JavaScript exploit stage high PDF_GENERIC_STAGE_RECOVERY
    Bounded static stage recovery exposed hidden JavaScript through generic transforms such as null-byte collapse, percent decoding, marker replacement, arithmetic character codes, fromCharCode, numeric arrays, or hex literals. This rule is emitted only when the recovered stage contains exploit-like Acrobat JavaScript or shellcode markers.
  • 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.
  • Embedded file low PDF_EMBEDDED
    PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload
  • 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)
  • PDF differential parser failed info PDF_DIFFERENTIAL_PARSE_FAILED
    The cross-check parser (pdfminer.six) failed on this file: PDF differential parser exited 1. Static heuristics still ran and any of their findings above are valid; only the differential cross-check signal is missing.
  • 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.
  • ClamAV scan did not complete on extracted artifact info CLAMAV_SCAN_INCOMPLETE
    ClamAV did not complete on 2 carved artifact(s); EXTRACTED_FILE_CLAMAV may be missing for this run. The result is not cached so a later submission will retry the scan.
  • 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_obj0032_000.js
0d657dbec0a810d630f49d5f02e55ace8d973e083a746f4aa7b3e1f3229c4029		 pdf-javascript-stream PDF /JS object 32 at offset 0x7E0 3935 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
generic_stage_recovery_000.js
b35a3ed5558b9f300c356062706a40ec10a5b772c5b5aee9145acd7f83ce8a48		 deobfuscated-js generic stage recovery percent-decode from JavaScript object 32 at offset 0x7E0 3731 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).

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