PDF malware analysis — malicious · 435fd540165f6786

MALICIOUS

PDF

118.4 KB

MD5: f570756ed13cc1906bb239122e8c9489 SHA-1: 7906e1235a7f60946cd4809ee64767ec2e6570d4 SHA-256: 435fd540165f67867f7a89ad1134ba58b40a2fa90096e8ec3c9521dea54a00a4

196 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File T1566.001 Spearphishing Attachment

This PDF file contains embedded JavaScript that utilizes eval() and fromCharCode functions, indicating obfuscated code execution. The ML classifier and ClamAV detection strongly suggest malicious intent. The primary function of the JavaScript appears to be downloading and executing a secondary payload, as suggested by the 'Large comment-padded JavaScript eval stager' heuristic. The ClamAV signature 'Pdf.Exploit.Agent-36086' further confirms its malicious nature.

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.

Filename	Kind	Source	Size
`javascript_obj0006_000.js` `c0542c0a337e86401d2f0a15f952c67cf187f222d753bbe615fcfc5e179aa3bf`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	627430 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` `ced2a6e1f253c9da203d50b9e6460c21c52e6308abc2dbbb7c3bb94b13604ba3`	deobfuscated-js	double percent-decoded annotation JavaScript at offset 0x143	262144 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 625 long base64-like blob(s).

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