PDF malware analysis — malicious · a1670371b4d44c79

MALICIOUS

PDF

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

MD5: b8cc62f8dbf0cc5c24a302c81c8a1044 SHA-1: 543640096bbecef8ae8d4d5aeb73f922eafd0f63 SHA-256: a1670371b4d44c792b3e89a367e1b32884056750b47a63e305369f92ade76246

96 Risk Score

Malware Insights

MITRE ATT&CK

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

This PDF file contains embedded JavaScript, indicated by the PDF_JAVASCRIPT and PDF_JS heuristics. The JavaScript stream utilizes `String.fromCharCode` and `eval()` calls, suggesting obfuscation and dynamic code execution. The ML classifier strongly flags this PDF as malicious. The primary intent appears to be the execution of arbitrary code, likely to download and run a second-stage payload, as evidenced by the embedded JavaScript artifact.

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` `d74effedc12167b131dfe7f3cdd922c52a3bf2710c2d6be10a35805efd333ea9`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	791 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).

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