PDF malware analysis — malicious · 5f407cb545a6f38e

MALICIOUS

PDF

15.8 KB

MD5: f6c10c51bad7852fbf51c09cb8961801 SHA-1: 1ebb12679eeb4b9deebd69592906c5ca23b22ac0 SHA-256: 5f407cb545a6f38e0f8f21174fd75660144f28095a25fd537d254999b4e12780

256 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

This PDF file contains obfuscated JavaScript that utilizes eval() and String.fromCharCode(), indicative of an exploit. The critical heuristic 'PDF_JS_EXPLOIT_CLUSTER' and ClamAV detection 'Pdf.Exploit.Agent-36086' strongly suggest it's designed to exploit a PDF vulnerability for client execution. The JavaScript likely acts as a stager to download and execute a secondary payload, a common technique for initial access via spearphishing attachments.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 8

PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER

PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
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` `9a3f31cf150946ab596435980109049cc63c0b3d2f297faf7d9cda7de6211c24`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	426133 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).
`stream_001_off00003b81.bin` `2b1dc42119aee29bb6e386a3483b7f94234ceaa81d94235c3d8fe486a69dc6e4`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0x3B81	300 bytes

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