PDF malware analysis — malicious · c3963fbe2f808a57

MALICIOUS

PDF

15.7 KB

MD5: 053276d3dcaa5f5874125b697e4350fc SHA-1: 3802b9261f29de926f5ca33fdb143cd9d6d6968b SHA-256: c3963fbe2f808a572fee584e4ee1b0f95ef95ab726033d322648d3a8247a8669

166 Risk Score

Malware Insights

MITRE ATT&CK

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

The PDF contains obfuscated JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', 'PDF_EVAL', and 'PDF_JS_LARGE_COMMENT_PADDED_EVAL'. The ClamAV detection 'Pdf.Exploit.Agent-36086' strongly suggests this is a malicious PDF exploiting a known vulnerability. The JavaScript is likely designed to download and execute a second-stage payload, although the exact mechanism is obscured.

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` `6aedee2661223d871745672952fe535e8e60ace8d61efb31a8b0acc8257bdd58`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	424738 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` `11797e108155f31fac1235fb0e86845027f4aec7d3f454b450ef6d61f8143e0b`	deobfuscated-js	double percent-decoded annotation JavaScript at offset 0x143	262144 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 536 long base64-like blob(s).

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