PDF malware analysis — malicious · 57aa87a361048131

MALICIOUS

PDF

22.4 KB Created: 2011-72-51 03:25:00 Authoring application: String.fromCharCode

MD5: d91317d4a3c60f33665ffad557e622ef SHA-1: 095f0418d2aa7a8e217067f8e7dc4fa47b78b4da SHA-256: 57aa87a361048131f69203730e8a84b852ec26b6e6f34f208adb94025dec510b

96 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell T1204.002 Malicious File: User Execution: Malicious File

This PDF file contains embedded JavaScript, indicated by the PDF_JAVASCRIPT and PDF_JS heuristics. The JavaScript stream utilizes `eval()` and `String.fromCharCode`, suggesting obfuscation to hide its true functionality. The ML classifier strongly flags this PDF as malicious. The primary function appears to be the execution of obfuscated JavaScript, likely to download and execute a second-stage payload.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 5

eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
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.
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_obj0001_000.js` `0d5c714b006047433a6e4e33c6b05bb3632d7806efbb1b7f31644c972d196d11`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	530 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).

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