Malicious PDF — malware analysis report

Static analysis result for SHA-256 23a3b9c9a6bc2d16…

MALICIOUS

PDF

15.7 KB
MD5: 8a21a9eeac8b60e3379c224c94df9300 SHA-1: 1a65d9fe2862f0960c22f2422fb76b76b9d1bbc0 SHA-256: 23a3b9c9a6bc2d167d690f3511e6be99ccfc4a212461c5c1401edd7957d53000
166 Risk Score

Malware Insights

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

The PDF file contains embedded JavaScript, including a high-severity heuristic for a large comment-padded JavaScript eval stager. This indicates the script is designed to deobfuscate and execute malicious code. The ClamAV detection 'Pdf.Exploit.Agent-36086' further confirms its malicious nature. The primary attack pattern involves exploiting PDF vulnerabilities to run this JavaScript, which likely acts as a downloader for further malicious activity.

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
fa5ee1810f0205d4b76b2075222bab3390e46221658f8f25070c364e74786110
pdf-javascript-stream PDF /JS object 6 at offset 0x143 424787 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
613106a3abf8f5c484b61df9e767ffb5eb57cbe4f7071ff6126a711c6599272e
deobfuscated-js double percent-decoded annotation JavaScript at offset 0x143 262144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 587 long base64-like blob(s).