PDF malware analysis — malicious · f653a966f05758ad

MALICIOUS

PDF

118.5 KB

MD5: 203f1d69f09553c8a130a0b3c840de74 SHA-1: a77b5ec25a065c7bdb78cd13e8a77d829f49fb07 SHA-256: f653a966f05758add28b15e035618d1c40f539ef7a380555d5dc6679b4f831d1

166 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF file contains multiple JavaScript streams, with one being a large, comment-padded eval stager. This indicates the primary function is to execute obfuscated JavaScript. The presence of 'eval()' and 'String.fromCharCode' calls strongly suggests the script is designed to decode and execute arbitrary code, likely a downloader for a second-stage payload. The ClamAV detection 'Pdf.Exploit.Agent-36086' further supports its malicious nature.

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` `c6bd368defd4289714b888e9fc15035de71ae3350a2f6096f7168e8cf96fdbc4`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	626909 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` `073e6fa01af41cf03b033bcde450bc0f8a904756318daed26deec17869f21940`	deobfuscated-js	double percent-decoded annotation JavaScript at offset 0x143	262144 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 622 long base64-like blob(s).

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