PDF malware analysis — malicious · b4a09c408ebd158b

MALICIOUS

PDF

118.4 KB

MD5: e5d522413ff3dfe39bfaab1942d2b14b SHA-1: 55daf5d6127d997a56691d9337a16fac742bf989 SHA-256: b4a09c408ebd158b48b648d249c0f41d806d44a55df44e334ff95e22ec342286

196 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

The sample is a PDF file flagged by ClamAV as 'Pdf.Exploit.Agent-36086'. Static analysis detected multiple high-severity heuristics related to JavaScript execution within the PDF, including 'PDF_EVAL' and 'PDF_JS_LARGE_COMMENT_PADDED_EVAL'. These indicate the presence of obfuscated JavaScript designed to execute arbitrary code. The ML classifier also strongly indicated maliciousness. The primary attack pattern involves exploiting PDF vulnerabilities to run this script, which is likely a stager for downloading and executing further malicious content.

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 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0006_000.js` `726ad06c9b9360c08e9d337195eb50a55995ae7cfbe24fab174b2d2df648b970`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	626257 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).

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