Malicious PDF — malware analysis report

Static analysis result for SHA-256 6951fe5ff8c9954a…

MALICIOUS

PDF

118.7 KB
MD5: eb8ab83e370004fd2deb7a7588ef467d SHA-1: 140405818f79455f07581b5d2f3aa4c77dd622ad SHA-256: 6951fe5ff8c9954ad39fbfbe8b4ad065a2f29ac880343bdc3ef636f623d1710b
256 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution

The PDF file contains embedded JavaScript that utilizes eval() and String.fromCharCode() functions, indicative of obfuscation and exploit attempts. Heuristics and ClamAV detection confirm this is a malicious PDF exploiting a known cluster. The primary function of the embedded JavaScript is to download and execute a second-stage payload, as suggested by the exploit cluster and ML classification.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 8

  • PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER
    PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
  • 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
4cad5a345f12991e69a9a8507723a2cacb88a231acbb41a43982dad144124f06
pdf-javascript-stream PDF /JS object 6 at offset 0x143 627309 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).
stream_002_off0001d8ce.bin
09dd4a3a32ff08afbaf23f88cd75e797e184590240beda6478a1aa2fcaa0c8ec
decompressed-pdf-stream PDF FlateDecoded stream at offset 0x1D8CE 200 bytes