Malicious PDF — malware analysis report

Static analysis result for SHA-256 0ccbcf75e496b3d6…

MALICIOUS

PDF

118.7 KB
MD5: acbab63081906b78a876acd640e59374 SHA-1: 10f8d4295e18ccc261e103f445b515699710c2e7 SHA-256: 0ccbcf75e496b3d65ea9c6ad2af893ae78f8c91eb2d894002e12196fe5b22dc2
256 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The critical PDF_JS_EXPLOIT_CLUSTER heuristic, along with PDF_EVAL and PDF_FROMCHARCODE firings, indicates the sample is designed to exploit a PDF vulnerability. The embedded JavaScript, though heavily obfuscated, is likely responsible for downloading and executing a secondary payload, as suggested by the ML_NYX_PDF_MALICIOUS classification and ClamAV detection. The presence of JavaScript streams and exploit-related heuristics strongly points to a malicious document used for initial compromise.

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
5bdecf755fa11dc7c45e04a3e81a24ef37f2c1187811cba0d78ac6a21e46afcb
pdf-javascript-stream PDF /JS object 6 at offset 0x143 627373 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
49fe373b7e3eb773097b33919ed652c8dff5e335ea80d26a08ba037543ce8dfa
deobfuscated-js double percent-decoded annotation JavaScript at offset 0x143 262144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 641 long base64-like blob(s).