Malicious PDF — malware analysis report

Static analysis result for SHA-256 c6376440a6fa475a…

MALICIOUS

PDF

118.6 KB
MD5: 4d3435052c76b450585b89fc1e3b5f09 SHA-1: ce231f4b44b4dd105fe2561557c035e6a9a3f4f4 SHA-256: c6376440a6fa475a5263516577c852f9ba8e0c2775841b77eb2215d5afe8d082
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 JavaScript/JScript T1204.002 Malicious File

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_EVAL'. The 'PDF_JS_LARGE_COMMENT_PADDED_EVAL' heuristic suggests a stager mechanism. ClamAV detection as 'Pdf.Exploit.Agent-36086' further confirms its malicious nature. The JavaScript is likely designed to download and execute a secondary payload, although the specific URLs or execution details are not directly extractable from the provided evidence.

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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0006_000.js
9ad083e8e06a078ad24dd6430c36b2355fff4863d7ea1a03574fd1025aa0fe54
pdf-javascript-stream PDF /JS object 6 at offset 0x143 626876 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).
legacy_pdfkit_stage_000.js
bb89fe1b6d9252a70963d6f4ad5bbd66f308dbca0fdd9a6ace3ec3113f4e2418
deobfuscated-js double percent-decoded annotation JavaScript at offset 0x143 262116 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 611 long base64-like blob(s).