PDF malware analysis — malicious · 657fa3428f8fed38

MALICIOUS

PDF

4.3 KB

MD5: 2f0ba9402b3e83004456b2cd0dbed5da SHA-1: 156f9eca534005fade13a0d2c0bc1a3d4b708c59 SHA-256: 657fa3428f8fed386fa680863ec4984f56871aa296389580135c19659a93e218

156 Risk Score

Malware Insights

MITRE ATT&CK

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

The PDF file contains obfuscated JavaScript, indicated by multiple heuristic firings including PDF_JAVASCRIPT, PDF_JS, and PDF_EVAL. The JavaScript is designed to download and execute a second-stage payload, as evidenced by the ML classifier's high confidence and the presence of a large, obfuscated JavaScript stream. The specific URL for the payload download could not be fully reconstructed due to obfuscation, but the embedded artifact name 'javascript_obj937085_000.js' is a key indicator.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

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.
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. (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_obj937085_000.js` `408781c1fb611de0a867db063a81c6f1db5dd6d72b2ba9a7637f951a2665684a`	pdf-javascript-stream	PDF /JS object 937085 at offset 0x137	8303 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).

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