Malicious PDF — malware analysis report

Static analysis result for SHA-256 a23a5d499beeb87e…

MALICIOUS

PDF

43.1 KB
MD5: 346512b94330164509c171634db93c5e SHA-1: a1b40d9a3994e1d6039db6dee82c63097afc3056 SHA-256: a23a5d499beeb87e7ee3514353f3896561825673a7570700877d78a412c46e25
102 Risk Score

Malware Insights

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

The PDF file was flagged as malicious by an ML classifier and contains embedded JavaScript. The JavaScript stream, identified as 'javascript_obj0012_000.js', exhibits obfuscation techniques including String.fromCharCode and ASCIIHexDecode filters, indicating an attempt to hide malicious code. This script is likely responsible for downloading and executing a second-stage payload, a common technique for initial access.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9999

Heuristics 7

  • ASCIIHexDecode filter (with exploit indicators) medium PDF_FILTER_HEX
    Hex-encoding filter present alongside exploit delivery indicators — often used to hide payload or shellcode bytes
  • 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.
  • XFA form low PDF_XFA
    PDF uses XML Forms Architecture — can contain script logic
  • 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://ns.adobe.com/xdp/
    • http://www.xfa.org/schema/xci/2.6/
    • http://www.xfa.org/schema/xfa-template/2.6/

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0012_000.js
c79b204825497b8ee0761ef0d7b744e7cd8fc286291b68b27f17058dcf1735f3		 pdf-javascript-stream PDF /JS object 12 at offset 0xA0B2 3915 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 3 eval/decoder/string-building token(s). Carved artifact contains 4 long base64-like blob(s). Carved artifact contains 4 long hex-escaped blob(s).
font_00_sfnt_off0000033c.bin
26f3e7c91c76e658576c1bbb605ddb8e33e657870ea2f8ad3b8fe8f80b303358		 pdf-font-stream PDF embedded font (sfnt) at offset 0x33C 65932 bytes

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