CVE-2023-27600: Vulnerability 2 in the codec_delete_XX() functions

OpenSIPS crashes when a malformed SDP body is received and is processed by the delete_sdp_line function in the sipmsgops module. This issue can be reproduced by calling the function with an SDP body that does not terminate by a line feed (i.e. \n).
The vulnerability was found while performing black-box fuzzing against an OpenSIPS server running a configuration that made use of the functions codec_delete_except_re and codec_delete_re. The same issue was also discovered while performing coverage guided fuzzing on the function codec_delete_except_re. The crash happens because the function delete_sdp_line expects that
an SDP line is terminated by a line feed (\n):

Impact

By abusing this vulnerability, an attacker is able to crash the server. It affects configurations containing functions that rely on the affected code, such as the function codec_delete_except_re.

Due to the sanity check that is performed in the del_lump function, exploitation of this issue will generate an abort in the lumps processing function, resulting in a Denial of Service.

Patches

This issue has been fixed by commit c6ab3bb.

References

Read more about this issue in the Audit Document section 3.3.

For more information

If you have any questions or comments about this advisory:

• Open an issue in the OpenSIPS GitHub
• Email us at [email protected]