Malicious PDF — malware analysis report

Static analysis result for SHA-256 186cc33dd50d36d9…

MALICIOUS

PDF

118.7 KB
MD5: bd1d233a477b9ca96a8d2cb8928199d2 SHA-1: 67f7acf7d3005afb8f9b91405a8956be2c324aa7 SHA-256: 186cc33dd50d36d966de0c2f928d38cdef813eb93d73b35d2319154305278646
256 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

This PDF file contains embedded JavaScript that utilizes eval() and String.fromCharCode(), common techniques for obfuscation and exploit execution. The heuristics indicate a PDF JavaScript exploit cluster and a large comment-padded JavaScript eval stager, strongly suggesting the document is designed to exploit a vulnerability and download a secondary payload. The ClamAV detection of 'Pdf.Exploit.Agent-36086' further confirms its malicious nature.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 8

  • PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER
    PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
  • ClamAV: Pdf.Exploit.Agent-36086 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36086
  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • Large comment-padded JavaScript eval stager high PDF_JS_LARGE_COMMENT_PADDED_EVAL
    PDF JavaScript contains a very large stream padded with long random-looking block comments around String.fromCharCode and eval. This is an exploit-kit obfuscation shape used to bury a decoder and recovered stage inside noise, not normal PDF form automation.
  • 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.
  • 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.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0006_000.js
04d7ce847970700aaf82d63593b3d452a1982a1bd782584198f744308e882631
pdf-javascript-stream PDF /JS object 6 at offset 0x143 627352 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 42 long base64-like blob(s).
stream_001_off0001d772.bin
86b9eff69df129c0edfd0b29a6fa69d72b71801c76cd8ebd4e4f65fc7dff9a68
decompressed-pdf-stream PDF FlateDecoded stream at offset 0x1D772 300 bytes