Malicious PDF — malware analysis report

Static analysis result for SHA-256 ac617b25953818ce…

MALICIOUS

PDF

9.2 KB Created: 2008-04-28 12:17:40 +03:00
MD5: 15192c723497b4791ba54c004cff4991 SHA-1: 8541ff4f3897b0ed5b53a831271bf07d11a26337 SHA-256: ac617b25953818ce6d69af5bb614657b6b46a9a99c2aa2d613287a6d783b1b93
66 Risk Score

Malware Insights

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

The PDF file was flagged by an ML classifier as malicious with a high confidence score. Static analysis revealed embedded JavaScript, including the use of String.fromCharCode, which is often used for obfuscation. The presence of an embedded JavaScript file (javascript_obj0016_000.js) strongly suggests an attempt to execute arbitrary code. This script likely serves as a downloader for a second-stage payload.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9999

Heuristics 7

  • 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)
  • Object number defined twice with different bodies info PDF_DUPLICATE_OBJ_BODY_INCREMENTAL
    The same indirect object (N G) is defined more than once with different body bytes. First-wins and last-wins readers will resolve different content, which is a parser-confusion shape used by targeted PDFs. Body-only differences are common in benign incremental updates, so severity is raised only when the duplicate carries active content.
  • 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/iX/1.0/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0016_000.js
88cb3b8c75b646591b816cc99ab91f4dfcc96decfdd2011d81483821b6762e4a		 pdf-javascript-stream PDF /JS object 16 at offset 0x931 6563 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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