Malicious PDF — malware analysis report

Static analysis result for SHA-256 b750203854268116…

MALICIOUS

PDF

174.0 KB Created: 2009-06-23 15:36:37 +08:00
MD5: efc1d105a4f2f4c14f0f900cff3424bc SHA-1: 1f7bb54885e906d142426322350b272290bcdc38 SHA-256: b750203854268116df07b5e641faa706bb3197de2be976384391a201dad7938a
104 Risk Score

Malware Insights

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

This PDF file contains embedded JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_EMBEDDED'. The JavaScript stream, specifically 'stream_004_off00000674.js', contains an 'eval()' call and uses 'String.fromCharCode', suggesting obfuscation. The ML classifier also flagged this PDF as malicious. The primary function of the embedded script appears to be downloading and executing a second-stage payload, though the exact URL is not directly extractable due to obfuscation. The benign URLs listed are standard RDF and Adobe namespaces and are not indicative of malicious activity.

Machine Learning

  • Nyx PDF Classifier malicious score 0.8800

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
9f863e4c538c25d2923eeaea7969b2f86922a9a4bdc9033c243d8ce75fb49f5a		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x674 3572 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
objstm_0026_00.bin
baff9946df1e799d07a756f256be83cffd595ab3192509f9b890eba794a603bb		 pdf-objstm-decoded PDF /ObjStm 26 0 obj (inflated) 306 bytes

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