CVE-2024-45004

In the Linux kernel, the following vulnerability has been resolved:

KEYS: trusted: dcp: fix leak of blob encryption key

Trusted keys unseal the key blob on load, but keep the sealed payload in the blob field so that every subsequent read (export) will simply convert this field to hex and send it to userspace.

With DCP-based trusted keys, we decrypt the blob encryption key (BEK) in the Kernel due hardware limitations and then decrypt the blob payload. BEK decryption is done in-place which means that the trusted key blob field is modified and it consequently holds the BEK in plain text. Every subsequent read of that key thus send the plain text BEK instead of the encrypted BEK to userspace.

This issue only occurs when importing a trusted DCP-based key and then exporting it again. This should rarely happen as the common use cases are to either create a new trusted key and export it, or import a key blob and then just use it without exporting it again.

Fix this by performing BEK decryption and encryption in a dedicated buffer. Further always wipe the plain text BEK buffer to prevent leaking the key via uninitialized memory.

Weakness

The product stores sensitive information in cleartext within a resource that might be accessible to another control sphere.

Affected Software

Extended Description

Because the information is stored in cleartext (i.e., unencrypted), attackers could potentially read it. Even if the information is encoded in a way that is not human-readable, certain techniques could determine which encoding is being used, then decode the information. When organizations adopt cloud services, it can be easier for attackers to access the data from anywhere on the Internet. In some systems/environments such as cloud, the use of “double encryption” (at both the software and hardware layer) might be required, and the developer might be solely responsible for both layers, instead of shared responsibility with the administrator of the broader system/environment.

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/37.html

References

• https://git.kernel.org/stable/c/0e28bf61a5f9ab30be3f3b4eafb8d097e39446bb
• https://git.kernel.org/stable/c/9e3b266afcfe4294e84496f50f006f029d3100db