gen_rand_uuid in lib/uuid.c in Das U-Boot v2014.04 through v2019.04 lacks an srand call, which allows attackers to determine UUID values in scenarios where CONFIG_RANDOM_UUID is enabled, and Das U-Boot is relied upon for UUID values of a GUID Partition Table of a boot device.
Weakness
The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers.
Affected Software
| Name |
Vendor |
Start Version |
End Version |
| U-boot |
Denx |
2014.04 (including) |
2019.04 (including) |
| U-boot |
Ubuntu |
cosmic |
* |
| U-boot |
Ubuntu |
disco |
* |
| U-boot |
Ubuntu |
esm-infra/xenial |
* |
| U-boot |
Ubuntu |
upstream |
* |
| U-boot |
Ubuntu |
xenial |
* |
Potential Mitigations
- Use a well-vetted algorithm that is currently considered to be strong by experts in the field, and select well-tested implementations with adequate length seeds.
- In general, if a pseudo-random number generator is not advertised as being cryptographically secure, then it is probably a statistical PRNG and should not be used in security-sensitive contexts.
- Pseudo-random number generators can produce predictable numbers if the generator is known and the seed can be guessed. A 256-bit seed is a good starting point for producing a “random enough” number.
References