Malicious PDF — malware analysis report

Static analysis result for SHA-256 4b6c9eded0f08f50…

MALICIOUS

PDF

15.7 KB
MD5: 220a41b07c8c615b37dbbb595841bbb1 SHA-1: dc05afd7f388a99cd243580f0ea3645d50f4b610 SHA-256: 4b6c9eded0f08f503e730bcb500dffc2c642f391fa129be73e3ebc95ed810d5e
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The PDF contains embedded JavaScript, which is heavily obfuscated and utilizes `eval()` and `String.fromCharCode()`. Heuristics indicate a large comment-padded JavaScript eval stager, suggesting it's designed to deobfuscate and execute further malicious code. The ClamAV detection 'Pdf.Exploit.Agent-36086' strongly supports the malicious nature of this file. The primary attack pattern involves leveraging JavaScript within the PDF 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0006_000.js
b9016a869610cca415f465fc207208620173753bf2f0eb4cfc96bc1be5ea8b43
pdf-javascript-stream PDF /JS object 6 at offset 0x143 425320 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).