The discovery of a high-severity vulnerability in Linux allows malware to be installed at the firmware level, providing attackers with access to the deepest parts of a device, making it difficult to detect and remove infections. The vulnerability resides in shim, an integral component that runs in the firmware early in the boot process. This vulnerability, referred to as CVE-2023-40547, is a buffer overflow bug that enables attackers to execute code of their choice. The exploit allows for the neutralization of the secure boot mechanism by executing malicious firmware at the earliest stages of the boot process.
Successful exploitation of the vulnerability can occur if the attacker coerces a system into booting from HTTP and either runs the HTTP server in question or performs a man-in-the-middle attack to subvert secure boot. While these hurdles are steep, they are not impossible, especially the ability to compromise or impersonate a server that communicates with devices over HTTP. Additionally, the ability to gain physical access to a device is also difficult and widely regarded as grounds for considering it to be already compromised.
In conclusion, the vulnerability in Linux poses a significant risk as it allows attackers to install malware at the firmware level, making it hard to detect and remove infections. While exploiting the vulnerability is challenging and requires meeting several conditions, it is not impossible, especially with unencrypted communication over HTTP. This discovery emphasizes the need for robust security measures and secure communication protocols to protect devices from firmware-level attacks.