Malicious PDF — malware analysis report

Static analysis result for SHA-256 e91d488d99419139…

MALICIOUS

PDF

15.7 KB
MD5: d2ef234d3a4505621e5971c106ac2291 SHA-1: 21e74342fc0a6dbd0dfd74635e881b38704b1004 SHA-256: e91d488d9941913959c6a3c57c5d902d3be1635ca8ebedc82e1a0926d84756f1
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File T1566.001 Spearphishing Attachment T1027 Obfuscated Files or Information

The PDF file contains heavily obfuscated JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', 'PDF_EVAL', and 'PDF_JS_LARGE_COMMENT_PADDED_EVAL'. The ClamAV detection 'Pdf.Exploit.Agent-36086' strongly suggests it's a known exploit. The JavaScript is designed to be executed, likely to download and run a secondary payload, which is a common technique for initial access and further infection.

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
15d102b81fd33e97a43c961e7e3afab98c996975c8555a68902a6d0926e349d1
pdf-javascript-stream PDF /JS object 6 at offset 0x143 426099 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
11ee0498c8d073eb078295e40993f58d3fc119e2ac3d0847366e3cd2489a417e
deobfuscated-js double percent-decoded annotation JavaScript at offset 0x143 262144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 612 long base64-like blob(s).