Malicious PDF — malware analysis report

Static analysis result for SHA-256 f4ccb4ca1e7c2e98…

MALICIOUS

PDF

118.5 KB
MD5: 01755f3165acec0e4c51e0b5ce1b89c0 SHA-1: 1086d2cd6069eb64415eb6121cdcec41afc3cdec SHA-256: f4ccb4ca1e7c2e98e060cb7b58517fe953dc781e37aea2a02f1fc8198a0d44cc
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File T1566.002 Spearphishing Attachment

The PDF file contains embedded JavaScript, with high-confidence heuristics indicating the use of eval() and a large comment-padded eval stager. ClamAV detection as 'Pdf.Exploit.Agent-36086' further confirms its malicious nature. The presence of JavaScript streams and eval calls strongly suggests the execution of arbitrary code, likely to download and execute a secondary payload.

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
c518891658e2c8506b94744b920cb162a6c6c8e6e1d200dedf091848cf4a8ceb
pdf-javascript-stream PDF /JS object 6 at offset 0x143 626939 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
79c94a6456d8b6f404a894b1c621de7773541c90481d3cdca5f4942e82c9e667
deobfuscated-js double percent-decoded annotation JavaScript at offset 0x143 262144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 657 long base64-like blob(s).