Malicious PDF — malware analysis report

Static analysis result for SHA-256 983eecaceca3e4a6…

MALICIOUS

PDF

757 B Created: 2011-72-51 03:25:00 Authoring application: t9.5*w,t4.t5*w,t8.5*w,8*w,t4.5*w,t6.5*w,t8.75*w,t5.75*w,15.t5*w,9.75*w,9.t5*w,t9.t5*w,14.t5*w,1t*w,14.t5*w
MD5: 49f159730b50375127ad6c701255caa5 SHA-1: 066fb18efcf226b8e9c965329450e0edde4f4389 SHA-256: 983eecaceca3e4a675b13dda25c7df2efd45f5d0bdf1e643ab73312ba4cea475
174 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings including PDF_JAVASCRIPT and PDF_JS_EXPLOIT_CLUSTER. The JavaScript uses String.fromCharCode, a common obfuscation technique for malicious PDFs. The ML classifier also flagged this PDF as malicious with high confidence. The script likely attempts to exploit a vulnerability within the PDF reader or download a secondary payload.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9999

Heuristics 5

  • 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.
  • Correlated malicious PDF JavaScript signals critical PDF_CORRELATED_MALICIOUS_JS
    PDF JavaScript or auto-action content is corroborated by exploit staging, ML, or suspicious extracted-artifact findings. This correlation promotes old exploit-kit PDFs that otherwise remain in the suspicious band because each individual signal is intentionally weighted conservatively.
  • JavaScript action low 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.
  • String.fromCharCode low PDF_FROMCHARCODE
    String.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules.