A security issue was discovered in the Kubernetes Image Builder where default credentials are enabled during the Windows image build process when using the Nutanix or VMware OVA providers. These credentials, which allow root access, are disabled at the conclusion of the build. Kubernetes clusters are only affected if their nodes use VM images created via the Image Builder project and the vulnerability was exploited during the build process, which requires an attacker to access the build VM and modify the image while the build is in progress.
Weakness
The product contains hard-coded credentials, such as a password or cryptographic key.
Extended Description
There are two main variations:
Potential Mitigations
- For outbound authentication: store passwords, keys, and other credentials outside of the code in a strongly-protected, encrypted configuration file or database that is protected from access by all outsiders, including other local users on the same system. Properly protect the key (CWE-320). If you cannot use encryption to protect the file, then make sure that the permissions are as restrictive as possible [REF-7].
- In Windows environments, the Encrypted File System (EFS) may provide some protection.
- For inbound authentication using passwords: apply strong one-way hashes to passwords and store those hashes in a configuration file or database with appropriate access control. That way, theft of the file/database still requires the attacker to try to crack the password. When handling an incoming password during authentication, take the hash of the password and compare it to the saved hash.
- Use randomly assigned salts for each separate hash that is generated. This increases the amount of computation that an attacker needs to conduct a brute-force attack, possibly limiting the effectiveness of the rainbow table method.
- For front-end to back-end connections: Three solutions are possible, although none are complete.
References