PDF malware analysis — malicious · 155bd9f2da73d337

MALICIOUS

PDF

15.8 KB

MD5: e3354b6988afff23f931999e3058e835 SHA-1: 1725aae68ba4d438d890a54d6a6b3d3997a2e090 SHA-256: 155bd9f2da73d33719d88e315d71c2ff5add6044cce56e6b5323e79e9424b92b

256 Risk Score

Malware Insights

MITRE ATT&CK

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

This PDF file contains embedded JavaScript that utilizes eval() and String.fromCharCode() functions, indicating an attempt to obfuscate malicious code. The critical heuristic 'PDF_JS_EXPLOIT_CLUSTER' and ClamAV detection 'Pdf.Exploit.Agent-36086' strongly suggest this is an exploit attempting to download and execute a secondary payload. The ML classifier also confirms a high probability of maliciousness.

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 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0006_000.js` `bc3f66bc65c653e4d064438c3cf6d53310b92b1912a6b4f3e01f1611bc08b1fd`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	425394 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).

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