OpenSSL PowerPC POLY1305 state corruption on vector registers
CVE-2023-6129 Published on January 9, 2024
POLY1305 MAC implementation corrupts vector registers on PowerPC
Issue summary: The POLY1305 MAC (message authentication code) implementation
contains a bug that might corrupt the internal state of applications running
on PowerPC CPU based platforms if the CPU provides vector instructions.
Impact summary: If an attacker can influence whether the POLY1305 MAC
algorithm is used, the application state might be corrupted with various
application dependent consequences.
The POLY1305 MAC (message authentication code) implementation in OpenSSL for
PowerPC CPUs restores the contents of vector registers in a different order
than they are saved. Thus the contents of some of these vector registers
are corrupted when returning to the caller. The vulnerable code is used only
on newer PowerPC processors supporting the PowerISA 2.07 instructions.
The consequences of this kind of internal application state corruption can
be various - from no consequences, if the calling application does not
depend on the contents of non-volatile XMM registers at all, to the worst
consequences, where the attacker could get complete control of the application
process. However unless the compiler uses the vector registers for storing
pointers, the most likely consequence, if any, would be an incorrect result
of some application dependent calculations or a crash leading to a denial of
service.
The POLY1305 MAC algorithm is most frequently used as part of the
CHACHA20-POLY1305 AEAD (authenticated encryption with associated data)
algorithm. The most common usage of this AEAD cipher is with TLS protocol
versions 1.2 and 1.3. If this cipher is enabled on the server a malicious
client can influence whether this AEAD cipher is used. This implies that
TLS server applications using OpenSSL can be potentially impacted. However
we are currently not aware of any concrete application that would be affected
by this issue therefore we consider this a Low severity security issue.
Vulnerability Analysis
CVE-2023-6129 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, with no impact on integrity, and a high impact on availability.
Weakness Type
Expected Behavior Violation
A feature, API, or function does not perform according to its specification.
Products Associated with CVE-2023-6129
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Affected Versions
OpenSSL:- Version 3.2.0 and below 3.2.1 is affected.
- Version 3.1.0 and below 3.1.5 is affected.
- Version 3.0.0 and below 3.0.13 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.