CVE-2024-53703: SonicWall SMA100 SSLVPN Vulnerability - A Comprehensive Guide on Stack-based Buffer Overflow in SonicWall's mod_httprp Library and Potential Code Execution

CVE-2024-53703 is a critical vulnerability in the SonicWall SMA100 SSLVPN firmware versions 10.2.1.13-72sv and earlier. The vulnerability lies in the mod_httprp library, which is loaded by the Apache web server in the firmware. Remote attackers can exploit this vulnerability to cause stack-based buffer overflow and potentially execute arbitrary code on affected systems. This long-read post covers the details of this vulnerability, code snippets, links to original references, and exploit details.

Vulnerability Details

The SonicWall SMA100 SSLVPN is a widely used secure remote access solution that provides organizations with secure access to their applications and data. However, a flaw in the mod_httprp library can lead to a stack-based buffer overflow, allowing an attacker to execute arbitrary code on the system. The mod_httprp library in question is loaded by the Apache web server, which is part of the SonicWall SMA100 SSLVPN firmware.

The vulnerability is caused by an improper handling of specific incoming HTTP requests, leading to a stack-based buffer overflow condition. This can allow an attacker to overwrite the function return address, hijack the control flow, and potentially execute arbitrary code.

Exploit Details

An attacker can exploit this vulnerability by sending a specially crafted HTTP request to the vulnerable server. The attacker will have to create an HTTP request with a very long request method string while also adding a large number of spaces within the URI path. This will trigger the buffer overflow in the mod_httprp library, leading to stack-based buffer overflow and potentially arbitrary code execution.

Here's a brief code snippet that demonstrates the vulnerability in the mod_httprp library

#define HTTP_REQUEST_METHOD_SIZE 200

void process_request(char *method, int method_length, char *path) {
    char buffer[HTTP_REQUEST_METHOD_SIZE];
    
    memcpy(buffer, method, method_length);
    buffer[HTTP_REQUEST_METHOD_SIZE - 1] = '\';
    
    // further processing of the HTTP request
}

int main() {
    char method[] = "OVERLY_LONG_AND_MALICIOUS_HTTP_REQUEST_METHOD";
    int method_length = sizeof(method);
    
    char path[] = "/path/with/large/number/of/spaces/due/to/uri/encoding";
    
    process_request(method, method_length, path);
}

This sample code demonstrates the potential buffer overflow scenario that can occur in the real-world mod_httprp library while processing malicious HTTP requests.

For more information about this vulnerability, please refer to the following original references

1. Official CVE details page: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-53703
2. SonicWall's advisory on this issue: https://www.sonicwall.com/support/product-notification/security-advisory-sonicwall-sma100-sslvpn-stack-based-buffer-overflow-vulnerability/210724133259222/

Mitigation Steps

SonicWall has released firmware updates to address this vulnerability. Users of affected SonicWall SMA100 SSLVPN firmware versions are strongly advised to update their firmware to version 10.2.1.14 or later. The updated firmware can be downloaded from the SonicWall support portal: https://www.mysonicwall.com

Conclusion

CVE-2024-53703 is a critical vulnerability affecting SonicWall SMA100 SSLVPN firmware versions 10.2.1.13-72sv and earlier. The vulnerability exists in the mod_httprp library loaded by the Apache web server and can potentially lead to stack-based buffer overflow and arbitrary code execution. Users are strongly encouraged to update their firmware to the latest version to protect their systems from this vulnerability.

Timeline

Published on: 12/05/2024 14:15:22 UTC
Last modified on: 12/05/2024 15:15:11 UTC