Malicious PDF — malware analysis report

Static analysis result for SHA-256 4cf5d8fc8f10c515…

MALICIOUS

PDF

118.6 KB
MD5: d727a5ab043cbafdc7b7969348eaa92f SHA-1: cfe4508c5fa2147b505a42f206a82f57cc63413f SHA-256: 4cf5d8fc8f10c51528a5448329517a5c4a0f02ebc407f9532ad8ad073c8b6a09
196 Risk Score

Malware Insights

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

The PDF contains embedded and obfuscated JavaScript, indicated by multiple PDF_JAVASCRIPT and PDF_JS heuristics, including a high-severity PDF_EVAL and a PDF_JS_LARGE_COMMENT_PADDED_EVAL. The ML classifier and ClamAV detection strongly suggest malicious intent, specifically an exploit targeting PDF vulnerabilities. The presence of JavaScript actions and eval calls points to the execution of arbitrary code, likely to download and run a second-stage payload.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

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
1d5b0476cd6c2862282b144e900c16f1f0ce92a13faf34543977ec32ce176147
pdf-javascript-stream PDF /JS object 6 at offset 0x143 627510 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
115e5734b4432bda82f813b360e37ff2c26dbf7913f2652e4a141bf173a9e189
deobfuscated-js double percent-decoded annotation JavaScript at offset 0x143 262144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 509 long base64-like blob(s).