PDF malware analysis — malicious · 135327315b8b38d8

MALICIOUS

PDF

20.8 KB Created: 2009-04-01 23:06:41 Authoring application: JXQw6onzo (via ytvx9rmh)

MD5: 8c77406a942ae59dce0acffc4f80352f SHA-1: 5f516249c1ed644282f36cb19b9cacc40c1ae06d SHA-256: 135327315b8b38d8d98b68fbc1a4c6bdfe98ff5b9c7a54be917f2994b91244f3

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 utilizes eval() and String.fromCharCode(), indicating obfuscated code execution. This JavaScript is likely designed to download and execute a second-stage payload, as suggested by the PDF_JS_EXPLOIT_CLUSTER heuristic. The ML classifier also strongly flagged this PDF as malicious.

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.
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_obj0007_000.js` `a75b607fe3a2dc969f7f683e47a9ee70dd346a120f88580f5b02e23b63ef1e6f`	pdf-javascript-stream	PDF /JS object 7 at offset 0x247	20031 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).

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