PDF malware analysis — malicious · 56b6d04acebb28bf

MALICIOUS

PDF

118.6 KB

MD5: 4b760aaf38adbd8485081aa4547167dc SHA-1: 640b8f9a2a84b5c50c0dc56664f7c6f8aff0659a SHA-256: 56b6d04acebb28bfdddbe4ee1e8842ef20c672dcd75d08a5ea897fc5dd0b7caf

166 Risk Score

Malware Insights

MITRE ATT&CK

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

This PDF file exhibits multiple high-severity heuristic firings related to JavaScript execution and obfuscation, including a 'Large comment-padded JavaScript eval stager'. ClamAV also detected it as 'Pdf.Exploit.Agent-36086'. The embedded JavaScript streams, particularly 'legacy_pdfkit_stage_000.js', are indicative of a stager designed to download and execute a second-stage payload. The presence of 'eval()' and 'String.fromCharCode' further supports the obfuscated nature of the script, common in exploit delivery.

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` `4b310c810089a7b1d31f639de5e9102f3cff60ffed64dbcf943eccb8b12323e7`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	627001 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` `8b97abe424e975ee787a0b1354c64f0bd7f3e98ceb34bd67f9df1054142e5425`	deobfuscated-js	double percent-decoded annotation JavaScript at offset 0x143	262144 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 589 long base64-like blob(s).

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