Malicious PDF — malware analysis report

Static analysis result for SHA-256 fbf9efa53b813812…

MALICIOUS

PDF

118.7 KB
MD5: 4391727c1170a53afd2205fc02488d74 SHA-1: 484287ad90d05832088aa23c3f850c32ef9e3b63 SHA-256: fbf9efa53b8138123437b384268918f823f4b2ac96539178992f6399a2ccd0be
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.001 Malicious Link

The PDF contains embedded JavaScript with multiple obfuscation techniques, including `eval()` calls and `String.fromCharCode`. A heuristic specifically flagged a 'Large comment-padded JavaScript eval stager'. ClamAV detection 'Pdf.Exploit.Agent-36086' further confirms its malicious nature. The primary attack pattern involves exploiting vulnerabilities within the PDF reader via the obfuscated JavaScript to achieve code execution.

Heuristics 7

  • 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
c7d0982fef6dcea9b69475d385b5d254d009f36bc5e46ede9763663ba452d14e
pdf-javascript-stream PDF /JS object 6 at offset 0x143 626842 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).