How to fix the booting issues caused after patching GRUB2 BootHole vulnerabilities

Overview:

Several vulnerabilities were brought to light in the GRUB2 bootloader that affected a wide range of operating systems. While vendors released security patches in a bid to mitigate these vulnerabilities, the patches for some RedHat and CentOS systems resulted in booting issues for some users. The vendors have recently released another update for the shim packages in order to fix the booting issue.

Solution:

To address the booting issue, RedHat and CentOS vendors have released patches for the systems. For more information, please refer to our blog:

Use SanerNow platform to apply this critical patch quickly across the organization as shown below.

SanerNow:

Vulnerability detection and patching of shim:

1.Login to SanerNow platform
2.Switch to the account/site specific view and Go to 'VM tool'.

If your Application is vulnerable, Saner lists the above CVEs in 'Top Vulnerabilities or 'Recently Discovered Vulnerabilities' as shown in the below diagram:

3. Search for this vulnerability in VM tool. If you are affected, apply the patch through PM -> Missing Patches.
4. Select 'Groups/Devices' in the 'Asset Source' section and click 'Apply'.
5. Select the product 'shim' from the 'Asset' section as shown in the below image:

6. Select ‘Apply Selected Patches’ at the rightmost corner. This will prompt for ‘Creating Patch Task’. Fill in ‘Task Name’ and ‘Remediation Schedule' as per your preference and click on ‘Apply Selected Patches' as shown below:

7. Remediation job will be created, which will fix the vulnerability by upgrading to the latest patch version.
Once remediation is done, the Saner agent automatically scans again and uploads the result to SanerNow as shown below:

Note: If you had already installed the security patches for shim packages, these packages will not be visible under the 'Security' tab. In this case, please select the 'Non-security' tab and follow the same procedure from step 4.