Malicious PDF — malware analysis report

Static analysis result for SHA-256 cfd8353dcfea0ca2…

MALICIOUS

PDF

15.7 KB
MD5: 6df3706a462645dcb9e6b89b40f19f40 SHA-1: 0d1751399e667585fa13a664be7c8f568c518404 SHA-256: cfd8353dcfea0ca2d380eb1cdbd361135515a17c5ebd10912b2e669c16fb871b
166 Risk Score

Malware Insights

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

The PDF file contains embedded JavaScript, including a large comment-padded eval stager, indicating an attempt to obfuscate malicious code execution. The presence of `eval()` and `String.fromCharCode` further suggests dynamic code generation and execution. ClamAV detection as 'Pdf.Exploit.Agent-36086' strongly suggests exploitation of a known PDF vulnerability. The primary function appears to be the execution of this JavaScript, which is designed 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
b2a7ff5b94751446bd878b34836e904c88c1ab1c71c1baad74d62e71370520a3
pdf-javascript-stream PDF /JS object 6 at offset 0x143 425648 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
7126f29900e352526c26578b53cd751ce80ff79ef424f1a5299ddf67bb275e53
deobfuscated-js double percent-decoded annotation JavaScript at offset 0x143 262144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 746 long base64-like blob(s).