PDF malware analysis — malicious · 9f21e867b9373677

MALICIOUS

PDF

118.5 KB

MD5: e0158c00950d91e96520ef9a6c7c9e21 SHA-1: 3604306a1cdecee02f74250a6a7f028157d2a449 SHA-256: 9f21e867b9373677a969376449059e5c586b9f18c016db937194159a97b81e81

196 Risk Score

Malware Insights

MITRE ATT&CK

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

The sample is a PDF file detected by ClamAV as 'Pdf.Exploit.Agent-36086'. Static analysis revealed multiple JavaScript-related heuristics, including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_EVAL', indicating the presence and execution of JavaScript code within the PDF. A large, comment-padded JavaScript eval stager was also identified. The ML classifier assigned a very high probability of maliciousness. The primary attack pattern involves leveraging these JavaScript capabilities to execute malicious code, likely for downloading and running further payloads.

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` `5f89c599405368fb04886ae33d29f0a3ef105fd129cffb5dfb6740f10f16bf21`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	627606 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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