Amazon Linux 2023 Security Advisory: ALAS2023-2023-344
Advisory Released Date: 2023-09-20
Advisory Updated Date: 2025-09-09
FAQs regarding Amazon Linux ALAS/CVE Severity
Wasmtime is a standalone runtime for WebAssembly. Prior to versions 6.0.2, 7.0.1, and 8.0.1, Wasmtime's implementation of managing per-instance state, such as tables and memories, contains LLVM-level undefined behavior. This undefined behavior was found to cause runtime-level issues when compiled with LLVM 16 which causes some writes, which are critical for correctness, to be optimized away. Vulnerable versions of Wasmtime compiled with Rust 1.70, which is currently in beta, or later are known to have incorrectly compiled functions. Versions of Wasmtime compiled with the current Rust stable release, 1.69, and prior are not known at this time to have any issues, but can theoretically exhibit potential issues.
The underlying problem is that Wasmtime's runtime state for an instance involves a Rust-defined structure called `Instance` which has a trailing `VMContext` structure after it. This `VMContext` structure has a runtime-defined layout that is unique per-module. This representation cannot be expressed with safe code in Rust so `unsafe` code is required to maintain this state. The code doing this, however, has methods which take `&self` as an argument but modify data in the `VMContext` part of the allocation. This means that pointers derived from `&self` are mutated. This is typically not allowed, except in the presence of `UnsafeCell`, in Rust. When compiled to LLVM these functions have `noalias readonly` parameters which means it's UB to write through the pointers.
Wasmtime's internal representation and management of `VMContext` has been updated to use `&mut self` methods where appropriate. Additionally verification tools for `unsafe` code in Rust, such as `cargo miri`, are planned to be executed on the `main` branch soon to fix any Rust-level issues that may be exploited in future compiler versions.
Precomplied binaries available for Wasmtime from GitHub releases have been compiled with at most LLVM 15 so are not known to be vulnerable. As mentioned above, however, it's still recommended to update.
Wasmtime version 6.0.2, 7.0.1, and 8.0.1 have been issued which contain the patch necessary to work correctly on LLVM 16 and have no known UB on LLVM 15 and earlier. If Wasmtime is compiled with Rust 1.69 and prior, which use LLVM 15, then there are no known issues. There is a theoretical possibility for undefined behavior to exploited, however, so it's recommended that users upgrade to a patched version of Wasmtime. Users using beta Rust (1.70 at this time) or nightly Rust (1.71 at this time) must update to a patched version to work correctly. (CVE-2023-30624)
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)
Affected Packages:
ecs-service-connect-agent
Issue Correction:
Run dnf update ecs-service-connect-agent --releasever 2023.2.20230920 or dnf update --advisory ALAS2023-2023-344 --releasever 2023.2.20230920 to update your system.
More information on how to update your system can be found on this page: Amazon Linux 2023 documentation
aarch64:
ecs-service-connect-agent-v1.27.0.0-1.amzn2023.aarch64
src:
ecs-service-connect-agent-v1.27.0.0-1.amzn2023.src
x86_64:
ecs-service-connect-agent-v1.27.0.0-1.amzn2023.x86_64