PDF malware analysis — malicious · 991bc9c261005435

MALICIOUS

PDF

118.4 KB

MD5: 88c4a2ba6abc7f3556dedf56544a1202 SHA-1: 039422aba7de8ab40249fe758dbd606052bb556e SHA-256: 991bc9c2610054352b82b59d99e616f43d1f7fc0b977be224b24fca550c6491c

166 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1059.007 JavaScript

The PDF contains embedded JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_EVAL'. The 'PDF_JS_LARGE_COMMENT_PADDED_EVAL' heuristic specifically points to a stager designed to execute obfuscated JavaScript. This stager is likely responsible for downloading and executing a secondary payload. The ClamAV detection 'Pdf.Exploit.Agent-36086' further confirms the malicious nature of the file.

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` `77adb423402441c3efc19434016022c0673dacda9ab048cd84811f8641d58204`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	627312 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` `17daf1dc2eefe7ebdc4c6bdfeb51175c6d5bb0709b8d1c6a448d7db28e024de9`	deobfuscated-js	double percent-decoded annotation JavaScript at offset 0x143	262116 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 585 long base64-like blob(s).

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