Description

Security researchers from Riot Games have identified a critical hardware-level vulnerability named “Sleeping Bouncer” affecting motherboards from ASUS, Gigabyte, MSI, and ASRock. The flaw exists in the system’s pre-boot protection process and allows attackers to inject malicious code during the earliest stages of system startup. Although security options such as Pre-Boot DMA Protection appear enabled in BIOS settings, the underlying hardware fails to activate these defenses correctly, leaving systems exposed before the operating system loads. Modern computers boot in a highly privileged state where firmware initializes hardware before handing control to the operating system. During this phase, components that load early have greater control over the system. The Sleeping Bouncer vulnerability exploits a failure in the IOMMU (Input-Output Memory Management Unit), which is designed to restrict unauthorized memory access by DMA-capable devices. Due to improper initialization, firmware falsely reports the protection as active, creating a short but dangerous window where attackers can gain elevated access, inject code, and hide before security software becomes operational. Motherboard vendors have released BIOS updates to fix this issue, and users should apply them immediately from official manufacturer websites. Organizations should enforce strict firmware update policies, enable hardware security features, and block access to sensitive systems if protections are disabled. Riot Games’ Vanguard will also enforce stricter checks, restricting gameplay on unpatched systems. Prompt remediation is critical to prevent stealthy, persistent compromise.