Malicious PDF — malware analysis report

Static analysis result for SHA-256 b40566d79c4ceb80…

MALICIOUS

PDF

15.7 KB
MD5: 1378fe28c16c3b7320646f88406dc538 SHA-1: bbe2dbffa734c63b3eb87f0d0341f6a20497b77f SHA-256: b40566d79c4ceb80aad9ddcb40402c582298a88d80cc022af4942d11db771794
166 Risk Score

Malware Insights

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

The PDF file contains embedded JavaScript, with high-confidence heuristics indicating the use of eval() and a large comment-padded JavaScript eval stager. ClamAV detected this as Pdf.Exploit.Agent-36086. The embedded JavaScript is likely responsible for downloading and executing a second-stage payload, which is a common technique for PDF-based malware delivery.

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
a8a60cee4e30aa37ea96ed20963ea221f08be7e8194fd0713abca5f872a36d9f
pdf-javascript-stream PDF /JS object 6 at offset 0x143 425812 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
9e898fbfa4bc9f05ca7a0b4115b5fcf126d9356c2a085a40ab69e81b508ab3d4
deobfuscated-js double percent-decoded annotation JavaScript at offset 0x143 262144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 479 long base64-like blob(s).