Vulnerabilities > CVE-2023-1998 - Information Exposure Through Discrepancy vulnerability in multiple products

047910
CVSS 5.6 - MEDIUM
Attack vector
LOCAL
Attack complexity
HIGH
Privileges required
LOW
Confidentiality impact
HIGH
Integrity impact
NONE
Availability impact
NONE
local
high complexity
linux
debian
CWE-203

Summary

The Linux kernel allows userspace processes to enable mitigations by calling prctl with PR_SET_SPECULATION_CTRL which disables the speculation feature as well as by using seccomp. We had noticed that on VMs of at least one major cloud provider, the kernel still left the victim process exposed to attacks in some cases even after enabling the spectre-BTI mitigation with prctl. The same behavior can be observed on a bare-metal machine when forcing the mitigation to IBRS on boot command line. This happened because when plain IBRS was enabled (not enhanced IBRS), the kernel had some logic that determined that STIBP was not needed. The IBRS bit implicitly protects against cross-thread branch target injection. However, with legacy IBRS, the IBRS bit was cleared on returning to userspace, due to performance reasons, which disabled the implicit STIBP and left userspace threads vulnerable to cross-thread branch target injection against which STIBP protects.

Vulnerable Configurations

Part Description Count
OS
Linux
5450
OS
Debian
1

Common Weakness Enumeration (CWE)