Malicious PDF — malware analysis report

Static analysis result for SHA-256 63c2e96a410231bb…

MALICIOUS

PDF

118.7 KB
MD5: cbac6c3e0f99ab73cf2485aeae7b5698 SHA-1: 5793123549f1cec07bb1e4892c90f1ba22eb3852 SHA-256: 63c2e96a410231bb71fa074e1cc90acaa7a858c7fab228053dd5c9c2086ca440
256 Risk Score

Malware Insights

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

The PDF file contains obfuscated JavaScript that utilizes eval() and String.fromCharCode(), indicating an attempt to exploit vulnerabilities and execute arbitrary code. The presence of PDF_JS_EXPLOIT_CLUSTER and ML_NYX_PDF_MALICIOUS heuristics, along with ClamAV detection as Pdf.Exploit.Agent-36086, strongly suggests malicious intent. The JavaScript is designed to download and execute a second-stage payload, a common technique for malware delivery.

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
4eb20f37e78d1288751dfd6f2eb612165853d818fb0ce288170b94620b8c7ecc
pdf-javascript-stream PDF /JS object 6 at offset 0x143 628132 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_001_off0001d721.bin
ee33d5c4221656ef3e63f60a57bda297e4fe0d954b652cd167a8e3bf018f8df8
decompressed-pdf-stream PDF FlateDecoded stream at offset 0x1D721 300 bytes