Malicious PDF — malware analysis report

Static analysis result for SHA-256 81f2d91ccac9aa77…

MALICIOUS

PDF

147.5 KB
MD5: ad064a61c3f5ca0929019a176516cbd4 SHA-1: cec2ec2367f2181f3b58832b8e0fd613922ed259 SHA-256: 81f2d91ccac9aa77ea0571307b02528b2a1bb4b590df32c88c66daa01fb8d10d
176 Risk Score

Malware Insights

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

The PDF sample contains embedded JavaScript, indicated by multiple heuristic firings including PDF_JAVASCRIPT, PDF_JS, and PDF_UNESCAPE. A critical ClamAV detection (Pdf.Exploit.Agent-36189) and an ML classifier further confirm its malicious nature. The embedded JavaScript is likely responsible for exploiting a vulnerability within the PDF reader to download and execute a second-stage payload from one of the unknown-reputation URLs. The document body content is heavily obfuscated and does not provide clear user-facing lures.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 8

  • ClamAV: Pdf.Exploit.Agent-36189 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36189
  • unescape() call high PDF_UNESCAPE
    unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
  • 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
  • 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
  • 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.bitstream.com
    • 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_obj0013_000.js
db35e4443e1e013308f010a3267833eb957fdf70f40bc58ec7d76a660d9c460b		 pdf-javascript-stream PDF /JS object 13 at offset 0x10531 27749 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
font_00_sfnt_off00000352.bin
a8f4d9b7d604c3c8a0bf3f9a31b9e952d467f98d118fdc784d95d689a14d8a33		 pdf-font-stream PDF embedded font (sfnt) at offset 0x352 65932 bytes

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