PDF malware analysis — malicious · af33d4af8457f22a

MALICIOUS

PDF

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

MD5: 2b8fb5489433d05dd452dc412f624d0a SHA-1: 0cc31e57531bb4ab5007a184cc1239132376a0bd SHA-256: af33d4af8457f22a6fb47ce13246407e0eb06e7a25b97d14211648dd1a66c29a

98 Risk Score

Malware Insights

MITRE ATT&CK

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

The PDF file contains embedded JavaScript, indicated by the PDF_JAVASCRIPT and PDF_JS heuristics. The JavaScript stream utilizes `eval()` and `String.fromCharCode`, suggesting obfuscation and dynamic code execution. The ML classifier strongly flags this PDF as malicious. The primary IOC is the embedded JavaScript file, which is likely responsible for downloading and executing a secondary 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` `0b22a51677fdce54f9b8c85e2fa46800efd8de5df20b5732ce491e55c151f2a4`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	508 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 6 eval/decoder/string-building token(s).

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