PDF malware analysis — malicious · 035355c8181cfd1f

MALICIOUS

PDF

70.1 KB

MD5: c1b06d8d55b6d4d1e81593f839896e4a SHA-1: c99a3d1c810c8fffa74998a3b02ba82712077985 SHA-256: 035355c8181cfd1f6188c4ce9aa6d0e94033514973adda2ca30cb5d96bf4fc34

158 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 an unescape function and a custom base64 decoding routine. This script is designed to decode a further payload, indicated by the 'ML_NYX_PDF_MALICIOUS' heuristic and the 'PDF_JS_EXPLOIT_CLUSTER' firing. The decoded content is likely malicious, aiming to execute further stages of an attack. The presence of XFA forms and JavaScript actions points towards exploitation of PDF vulnerabilities.

Machine Learning

Nyx PDF Classifier malicious score 0.9998

Heuristics 7

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.
unescape() call high PDF_UNESCAPE

unescape() found — often used to decode shellcode in PDF JS exploits
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.
XFA form low PDF_XFA

PDF uses XML Forms Architecture — can contain script logic
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.bitstream.com
- http://ns.adobe.com/xdp/
- http://www.xfa.org/schema/xci/2.6/
- http://www.xfa.org/schema/xfa-template/2.6/

Extracted artifacts 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0013_000.js` `f234be0d4988095ef2dd72c376a7b210c8712972950dadd083812b139391366d`	pdf-javascript-stream	PDF /JS object 13 at offset 0x10531	3967 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
`javascript_obj0013_001.js` `fde576fdbb735e8f5543ebc1b2fc207e795f060360330311c50e5aced8f9461f`	pdf-javascript-stream	PDF /JS object 13 at offset 0x10555	4878 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
`font_00_sfnt_off00000352.bin` `a8f4d9b7d604c3c8a0bf3f9a31b9e952d467f98d118fdc784d95d689a14d8a33`	pdf-font-stream	PDF embedded font (sfnt) at offset 0x352	65932 bytes

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