PDF malware analysis — malicious · 53b8a02f38e9d4a7

MALICIOUS

PDF

118.5 KB

MD5: f9a7383edbbd1ea6e19d0f247210648b SHA-1: 8ee9dc6b592f0ca385ad12ee21e99d075fd3d261 SHA-256: 53b8a02f38e9d4a78be4aa8d65ea50e58a95c2138d0590df533091e8f702f461

196 Risk Score

Malware Insights

MITRE ATT&CK

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

This PDF file contains embedded JavaScript that utilizes eval() and String.fromCharCode, indicating a stager designed to execute malicious code. The ML classifier and ClamAV detection strongly suggest malicious intent, likely involving the download and execution of a secondary payload. The presence of a large, padded JavaScript eval stager further supports this, pointing towards an exploit delivery mechanism.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

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` `c13b5771e858eff891df18526f4329bec7dd612ee1247a37191c94dbe36d477b`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	627344 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_off0001d698.bin` `8f74265636cba98585de64b5f29714b2795e2ffb38834e56a1ba2352ea242921`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0x1D698	300 bytes

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