PDF malware analysis — malicious · 681f9da89675937e

MALICIOUS

PDF

3.8 KB

MD5: 82c8bf19c96840a46c3ba56f3fc16dff SHA-1: 78a4105d0bb9b9c1398e878107cfd669690b7db2 SHA-256: 681f9da89675937ed908ba152862107df5035aa6e533d56b407cae6e70a60fdd

156 Risk Score

Malware Insights

MITRE ATT&CK

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

The PDF contains obfuscated JavaScript, indicated by the use of eval() and String.fromCharCode, and flagged by the PDF JavaScript exploit cluster heuristic. The script appears to be designed to decode and execute a second-stage payload from embedded strings. The ML classifier strongly indicates maliciousness, and the overall pattern suggests a spearphishing attachment used to deliver further malware.

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 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj111711_000.js` `3a787e8ec8919a08c65e6d3c07b0ab46e51b78f0069fba5f1d00ac47a78ce802`	pdf-javascript-stream	PDF /JS object 111711 at offset 0x197	4808 bytes
`javascript_obj111712_001.js` `dcdf695d6da4b09712aae7de19c85419b2d7aaff093a6e78285ab88c8aa73721`	pdf-javascript-stream	PDF /JS object 111712 at offset 0xD67	538 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).

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