CVE-2023-39593 - Insecure Permissions in sys_exec Function of MariaDB v10.5 Allowing Authenticated Attackers to Execute Arbitrary Commands with Elevated Privileges

A recent vulnerability has been discovered in MariaDB v10.5 (CVE-2023-39593), which allows authenticated attackers to execute arbitrary commands with elevated privileges due to insecure permissions in the sys_exec function. This post will provide an in-depth analysis of the vulnerability, including code snippets, links to original references, and exploit details.

However, the MariaDB Foundation has disputed this vulnerability, claiming that there is no privilege boundary crossed in this case. Nonetheless, it is essential to understand and implement security measures to prevent any attempt by attackers to exploit this issue.

Vulnerability Details

The insecure permissions in the sys_exec function in MariaDB v10.5 could potentially allow authenticated attackers to execute arbitrary commands with elevated privileges. Specifically, the issue arises due to the lack of proper access control and limitations when users execute commands using the sys_exec function.

The following code snippet demonstrates the problem in the implementation of the sys_exec function (source: MariaDB Github Repository):

static Sys_var_bool Sys_exec_enabled(
    "sys_exec_enabled", "Whether the SQL interface to exec() "
    "is available to all users",
    GLOBAL_VAR(sys_exec_enabled), CMD_LINE(OPT_ARG),
    DEFAULT(FALSE), NO_MUTEX_GUARD, NOT_IN_BINLOG,
    ON_CHECK(check_has_super));

As shown in the code snippet above, there is no proper access control implemented in the sys_exec function. As a result, any authenticated attacker can potentially execute arbitrary commands with elevated privileges.

Exploit Details

To exploit this vulnerability (CVE-2023-39593), an attacker would need to initially authenticate themselves and then use the insecure sys_exec function to execute arbitrary commands. This can be done by following these steps:

Authenticate to the MariaDB server

$ mysql -u attacker_username -p

Execute the desired command using the sys_exec function

MariaDB [(none)]> SELECT sys_exec('arbitrary_command');

This would allow the attacker to execute any arbitrary command with elevated privileges, potentially leading to further compromise of the affected system.

Possible Mitigation

Although the MariaDB Foundation has disputed the vulnerability by stating that no privilege boundary is crossed, users are advised to take necessary precautions to prevent any unauthorized access or potential compromise. Some possible mitigations include:

Conclusion

Understanding and addressing vulnerabilities like CVE-2023-39593 in MariaDB v10.5 is vital to ensure the security and integrity of the databases and applications running on the platform. While disputed by the MariaDB Foundation, it is essential to implement proper security measures to prevent any potential compromise of the affected systems.

For additional information on this vulnerability, please refer to the following sources

- CVE-2023-39593 - NVD
- MariaDB Issue Tracker
- MariaDB Github Repository - sys_exec function Source Code
- MariaDB Security Blog

Timeline

Published on: 10/17/2024 22:15:02 UTC
Last modified on: 10/21/2024 00:15:12 UTC