Malicious PDF — malware analysis report

Static analysis result for SHA-256 c38fc555ea842d46…

MALICIOUS

PDF

118.5 KB
MD5: 850a6c196831629ae6c78ce75e9a0de4 SHA-1: f75fc15e4529bc970578e61b2996afeb41c3985c SHA-256: c38fc555ea842d46ccaaa681b1062c5f0ef3dd30cef07de8e6ae3c965892b4ff
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The PDF file contains embedded JavaScript, with high-confidence heuristics indicating the use of eval() and a large comment-padded JavaScript eval stager. ClamAV detection as 'Pdf.Exploit.Agent-36086' strongly suggests malicious intent. The embedded JavaScript is likely responsible for downloading and executing a second-stage payload, although the specific details are obfuscated. The presence of multiple JavaScript streams and the use of eval() point towards a common PDF exploit delivery mechanism.

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
3548696153a63ad895d2b66a6401716c1bc50ddde3f622f0e41798c525c839c1
pdf-javascript-stream PDF /JS object 6 at offset 0x143 627021 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
e1f735610047eb05e2fa02705dce20b329c9a95074168f4310f0a6f49d9c6a89
deobfuscated-js double percent-decoded annotation JavaScript at offset 0x143 262144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 575 long base64-like blob(s).