Malicious PDF — malware analysis report

Static analysis result for SHA-256 65d5ed5e79b4f65d…

MALICIOUS

PDF

15.7 KB
MD5: 6b62a262a48e7742afd7b0b492176349 SHA-1: 4cf33adce18dec81ffda6813193ac370f8a5b038 SHA-256: 65d5ed5e79b4f65d5880953cdb2c765dc229e098a22c42bfa7f4f1daa5b04fe0
256 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution

The PDF sample contains obfuscated JavaScript that utilizes eval() and String.fromCharCode(), indicative of an exploit. The ML classifier and ClamAV detection strongly suggest malicious intent. The JavaScript is designed to download and execute a second-stage payload, as evidenced by the PDF_JS_EXPLOIT_CLUSTER and PDF_JS_LARGE_COMMENT_PADDED_EVAL heuristics.

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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0006_000.js
5d4b1db16b47e83f11767b4fb36b70938b70bbd9f3270e06c974f33a2fefc7a4
pdf-javascript-stream PDF /JS object 6 at offset 0x143 424571 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).