PDF malware analysis — malicious · 237a539f3563b82b

MALICIOUS

PDF

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

MD5: c8e3d749404e699d08649f67a7abd0cb SHA-1: ef7f7c725a502cb627731eee3967c58f9713bd4c SHA-256: 237a539f3563b82b0ec81277d8295990160fa7c765e4c14a078d56fe45fd94ca

96 Risk Score

Malware Insights

MITRE ATT&CK

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

This PDF sample was flagged as malicious by an ML classifier and contains embedded JavaScript. The JavaScript stream utilizes `eval()` and `String.fromCharCode`, indicating obfuscation. The primary function of the script appears to be the execution of further malicious code, likely a downloader for a second-stage payload, as suggested by the heuristic firings and the presence of an embedded JavaScript file. The confidence is high due to the ML classification and the clear presence of obfuscated JavaScript designed for execution.

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` `16b4e5a3fbbb0e2a6771e05c905682b7c855627c0df7aeafcf73ec40f914419c`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	510 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 6 eval/decoder/string-building token(s).

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