PDF malware analysis — malicious · 85f0279835ff8def

MALICIOUS

PDF

174.0 KB Created: 2009-08-17 21:45:05 +08:00

MD5: c0c8f40b62d4ac42591bdb292f38f5ad SHA-1: 6365db0da95c52b37aeae46d0da306e7ea9463c2 SHA-256: 85f0279835ff8defbaa4f325e747359feab927217499d964a60592696095bd66

166 Risk Score

Malware Insights

MITRE ATT&CK

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

The PDF contains embedded JavaScript that utilizes eval() and String.fromCharCode(), indicating obfuscated code execution. This JavaScript is likely designed to download and execute a secondary payload, as suggested by the 'PDF JavaScript exploit cluster' heuristic. The ML classifier also flagged the PDF as malicious with a high probability.

Machine Learning

Nyx PDF Classifier malicious score 0.8846

Heuristics 8

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. (matched inside decoded stream)
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. (matched inside decoded stream)
Embedded file low PDF_EMBEDDED

PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload (matched inside decoded stream)
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.
Embedded URL info EMBEDDED_URL

One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
URL http://www.w3.org/1999/02/22-rdf-syntax-ns#
- http://ns.adobe.com/xap/1.0/
- http://purl.org/dc/elements/1.1/
- http://ns.adobe.com/xap/1.0/mm/
- http://ns.adobe.com/pdf/1.3/

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`stream_004_off00000674.js` `5ff92f5502ee1cae01cbaad9a28aea7c3f90a417f1ea57fecc297ac6c7f18e5c`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0x674	3658 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`objstm_0026_00.bin` `e64642f7d054b6fe06eb3d71d841961a918a29f4bb39c60d85d7a97b6273524b`	pdf-objstm-decoded	PDF /ObjStm 26 0 obj (inflated)	306 bytes

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