A recently identified security vulnerability known as CVE-2024-4741 involves the OpenSSL API function, SSL_free_buffers. In certain situations, calling this function may cause the application to access memory that has been previously freed, which results in a use-after-free condition.

Impact Summary

A use-after-free vulnerability can lead to various harmful consequences, such as data corruption, application crashes, or execution of arbitrary code. However, it is important to note that only applications that directly call the SSL_free_buffers function are affected by this issue. Applications that do not call this function are not vulnerable. Investigation into the matter shows that this function is rarely used by applications.

Details of the Vulnerability

The SSL_free_buffers function is typically used to free the internal OpenSSL buffer when processing incoming records from the network. The function is expected to be successful only if the buffer is not currently in use. However, two scenarios have been identified in which the buffer can be freed while still in use.

Scenario 1

The first scenario occurs when a record header is received and processed by OpenSSL, but the full record body has not yet arrived. In this case, calling SSL_free_buffers will succeed even though a record has only been partially processed and the buffer is still in use. A sample code snippet is shown below:

// Receive the record header
receive_record_header();
// Process the header
process_record_header();
// Call SSL_free_buffers
SSL_free_buffers(ssl);

Scenario 2

The second scenario occurs when a full record containing application data has been received and processed by openssl, but the application has only read part of the data. Again, calling SSL_free_buffers will succeed even though the buffer is still in use. A sample code snippet is shown below:

// Receive and process the full record
receive_and_process_full_record();
// Read part of the application data
read_partial_data();
// Call SSL_free_buffers
SSL_free_buffers(ssl);

Exploit Possibilities and Prevention

While these scenarios could occur accidentally during normal operation, a malicious attacker could attempt to engineer a situation where the vulnerability is exploited. However, it must be noted that no active exploits of this issue have been reported yet.

Organizations and developers that rely on OpenSSL to secure their applications should be on the lookout for security updates and patches addressing this vulnerability. OpenSSL developers should ensure that the SSL_free_buffers function is only called when the buffer is not in use to mitigate the risk of the use-after-free vulnerability.

It is important to know that the FIPS modules in OpenSSL versions 3.3, 3.2, 3.1, and 3. are not affected by this issue.

For more information about this vulnerability, please refer to the original OpenSSL Security Advisory and the CVE-2024-4741 entry in the Common Vulnerabilities and Exposures (CVE) database.

In conclusion, the CVE-2024-4741 vulnerability affects a limited number of applications using the OpenSSL API function 'SSL_free_buffers'. By staying informed about updates and patches, and ensuring proper usage of the affected function, developers can effectively mitigate the risks associated with this issue.

Timeline

Published on: 11/13/2024 11:15:04 UTC
Last modified on: 11/13/2024 15:35:12 UTC