Constrained Language Mode Bypass When __PSLockDownPolicy Is Used
Summary
This article discusses a bypass vulnerability in PowerShell's Constrained Language Mode (CLM) when the __PSLockDownPolicy is utilized. CLM is intended to reduce the attack surface by limiting available functionality, and this bypass potentially undermines those security measures.
IFF Assessment
The vulnerability discovered allows attackers to bypass security restrictions, which is bad news for defenders trying to maintain a secure environment.
Severity
This vulnerability likely involves a moderate attack complexity and low user interaction, allowing an attacker to bypass restrictions and execute commands, leading to potential unauthorized access or privilege escalation.
Defender Context
This finding highlights a critical bypass of a security feature designed to limit PowerShell's attack surface. Defenders should be aware of this bypass mechanism and investigate its applicability in their environments, especially those relying on CLM for security controls.