ROS-2-524

2.524 Multiple vulnerabilities in ISC BIND (CVE-2021-25216, CVE-2021-25215, CVE-2021-25214)

1. Vulnerability Description:

CVE-2021-25216 A vulnerability exists due to a boundary error in the GSS-TSIG extension. A remote attacker can send specially crafted requests to the server, trigger a buffer overflow and execute arbitrary code on the system. To successfully exploit the vulnerability, named must be configured to use the SPNEGO implementation by setting values for the tkey-gssapi-keutab or tkey-gssapi-credential configuration parameters (often used with Samba, and in mixed server environments that combine BIND servers with Active Directory domain controllers). CVE-2021-25215 A vulnerability exists due to an achievable assertion when processing DNAME records. A remote attacker could cause named to add the same set of RRset to the ANSWER partition more than once, cause an assertion failure and service failure. This issue affects both authoritative and recursive servers during zone transfers. CVE-2021-25214 A vulnerability exists due to achievable assertion when IXFR requests are pushed. An IXFR stream containing SOA records with an owner name different from the top of the transferred zone can cause the receiving server to inadvertently delete the SOA record for the zone in question from the zone database. This results in an assertion error when the next SOA update request for that zone is executed. When a vulnerable version of named receives a garbled IXFR triggering the error described above, the named process will terminate due to an assertion failure on the next update of the transmitted secondary zone.FSTEC Russia Information Security Threat Data Bank Identifier: BDU:2021-02773, BDU:2021-02778, BDU:2021-02777

2. Possible measures to eliminate the vulnerability

Refuse to use Bind or - install security updates for package: bind**Installing updates is possible in the following ways:**a) if the computer with the installed OS version has access to the vendor’s official repository, run the update as administrator with the command:# yum updateAfter the list of updated packages is displayed, agree to apply the updates by pressing the Y key on the keyboard. Wait until the update installation is complete and make sure that there are no errors during its installation.b)If the computer with the installed OS version does not have access to the vendor’s official repository, you should perform the following actions: - download the updated package (with dependencies if necessary): http://repo.red-soft.ru/redos/7.2c/x86_64/updates/bind-9.11.4-9.P2.el7.x86_64.rpm Check the integrity and authenticity of the package according to instructionsInstall the downloaded package(s) with the command:# yum localinstall *.rpmWhen the list of updated packages is displayed, agree to apply the updates by pressingY on the keyboard. Wait for the updates to finish installing and make sure there are no errors during the installation.

Date of last modification: 08.09.2021