Malicious PDF — malware analysis report

Static analysis result for SHA-256 280688dc29b19aae…

MALICIOUS

PDF

15.7 KB
MD5: 25b1aa4a7c0aa63c657667a5c8b0df28 SHA-1: 26b7c216103aefa6a13f0b514ea2a749695156d7 SHA-256: 280688dc29b19aae0c9f90cab2971196fbe650debe406f7b6b2eba7f682813f8
166 Risk Score

Malware Insights

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

The PDF file contains embedded JavaScript with multiple obfuscation techniques, including `eval()` calls and `String.fromCharCode`. Heuristics indicate a large comment-padded JavaScript eval stager, strongly suggesting it's designed to download and execute a secondary payload. ClamAV detection as 'Pdf.Exploit.Agent-36086' further confirms its malicious nature. The document body is unreadable, so the rationale is based solely on the script and heuristics.

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
43a5eced6939407b2c431ce6ffa5b00b0acf41df504b67a7b0667a2033386d1b
pdf-javascript-stream PDF /JS object 6 at offset 0x143 425432 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).