PDF malware analysis — malicious · 749b2b99f5861482

MALICIOUS

PDF

11.5 KB Created: 2009-02-19 14:45:49 -02:00 Authoring application: Writer (via OpenOffice.org 3.0)

MD5: 5a6d58c510514f300e75f03712b49fa1 SHA-1: 4dc2af2b55b269c3a3d769a79d047bd39636f593 SHA-256: 749b2b99f5861482686a68861ae452ec96df02e0baed1b8deff4863c18359e1d

156 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The PDF file contains embedded JavaScript that is heavily obfuscated using String.fromCharCode and other methods. Heuristics indicate this JavaScript is part of an exploit cluster, likely leveraging a known PDF vulnerability to achieve code execution. The script's primary function appears to be downloading and executing a secondary payload, as suggested by the obfuscated string construction which likely resolves to a URL or executable path. The ML classifier strongly flags this PDF as malicious.

Machine Learning

Nyx PDF Classifier malicious score 0.9999

Heuristics 6

PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER

PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
Launch action high PDF_LAUNCH

PDF contains a /Launch action with an unresolved or extension-less target — treat as potentially dangerous
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 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0025_000.js` `918a028b75565eadc9ceb324edd171ed4b66c6a9902c590c85ba0d54d9739e78`	pdf-javascript-stream	PDF /JS object 25 at offset 0x21AD	12706 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).

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