CVE Vulnerabilities

CVE-2017-11671

Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

Published: Jul 26, 2017 | Modified: Apr 12, 2018
CVSS 3.x
4
MEDIUM
Source:
NVD
CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CVSS 2.x
2.1 LOW
AV:L/AC:L/Au:N/C:P/I:N/A:N
RedHat/V2
RedHat/V3
Ubuntu

Under certain circumstances, the ix86_expand_builtin function in i386.c in GNU Compiler Collection (GCC) version 4.6, 4.7, 4.8, 4.9, 5 before 5.5, and 6 before 6.4 will generate instruction sequences that clobber the status flag of the RDRAND and RDSEED intrinsics before it can be read, potentially causing failures of these instructions to go unreported. This could potentially lead to less randomness in random number generation.

Weakness

The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG’s algorithm is not cryptographically strong.

Affected Software

Name Vendor Start Version End Version
Gcc Gnu 6.3 6.3
Gcc Gnu 6.2 6.2
Gcc Gnu 5.3 5.3
Gcc Gnu 5.1 5.1
Gcc Gnu 4.8 4.8
Gcc Gnu 6.0 6.0
Gcc Gnu 4.7 4.7
Gcc Gnu 5.4 5.4
Gcc Gnu 5.2 5.2
Gcc Gnu 5.0 5.0
Gcc Gnu 6.1 6.1
Gcc Gnu 4.9 4.9
Gcc Gnu 4.6 4.6

Extended Description

When a non-cryptographic PRNG is used in a cryptographic context, it can expose the cryptography to certain types of attacks. Often a pseudo-random number generator (PRNG) is not designed for cryptography. Sometimes a mediocre source of randomness is sufficient or preferable for algorithms that use random numbers. Weak generators generally take less processing power and/or do not use the precious, finite, entropy sources on a system. While such PRNGs might have very useful features, these same features could be used to break the cryptography.

Potential Mitigations

References