ALAS2023-2023-198

A flaw was found in the c-ares package. The ares_set_sortlist is missing checks about the validity of the input string, which allows a possible arbitrary length stack overflow. This issue may cause a denial of service or a limited impact on confidentiality and integrity. (CVE-2022-4904)

When cross-compiling c-ares and using the autotools build system, CARES_RANDOM_FILE will not be set, as seen when cross compiling aarch64 android. This will downgrade to using rand() as a fallback which could allow an attacker to take advantage of the lack of entropy by not using a CSPRNG. (CVE-2023-31124)

ares_inet_net_pton() is vulnerable to a buffer underflow for certain ipv6 addresses, in particular "0::00:00:00/2" was found to cause an issue. C-ares only uses this function internally for configuration purposes which would require an administrator to configure such an address via ares_set_sortlist().

However, users may externally use ares_inet_net_pton() for other purposes and thus be vulnerable to more severe issues. (CVE-2023-31130)

Insufficient randomness in generation of DNS query IDs

When /dev/urandom or RtlGenRandom() are unavailable, c-ares uses rand() to generate random numbers used for DNS query ids. This is not a CSPRNG, and it is also not seeded by srand() so will generate predictable output.
Input from the random number generator is fed into a non-compilant RC4 implementation and may not be as strong as the original RC4 implementation.
No attempt is made to look for modern OS-provided CSPRNGs like arc4random() that is widely available. (CVE-2023-31147)

Denial of Service.

Attack Steps:

The target resolver sends a query
The attacker forges a malformed UDP packet with a length of 0 and returns them to the target resolver
The target resolver erroneously interprets the 0 length as a graceful shutdown of the connection. (this is only valid for TCP connections, UDP is connection-less)
Current resolution fails, DoS attack is achieved. (CVE-2023-32067)

aarch64:
    c-ares-debugsource-1.19.0-1.amzn2023.aarch64
    c-ares-debuginfo-1.19.0-1.amzn2023.aarch64
    c-ares-1.19.0-1.amzn2023.aarch64
    c-ares-devel-1.19.0-1.amzn2023.aarch64

src:
    c-ares-1.19.0-1.amzn2023.src

x86_64:
    c-ares-debugsource-1.19.0-1.amzn2023.x86_64
    c-ares-debuginfo-1.19.0-1.amzn2023.x86_64
    c-ares-1.19.0-1.amzn2023.x86_64
    c-ares-devel-1.19.0-1.amzn2023.x86_64