CVE-2024-20265 in Aironet Access Point
Summary
by MITRE • 03/27/2024
A vulnerability in the boot process of Cisco Access Point (AP) Software could allow an unauthenticated, physical attacker to bypass the Cisco Secure Boot functionality and load a software image that has been tampered with on an affected device.
This vulnerability exists because unnecessary commands are available during boot time at the physical console. An attacker could exploit this vulnerability by interrupting the boot process and executing specific commands to bypass the Cisco Secure Boot validation checks and load an image that has been tampered with. This image would have been previously downloaded onto the targeted device. A successful exploit could allow the attacker to load the image once. The Cisco Secure Boot functionality is not permanently compromised.
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Analysis
by VulDB Data Team • 03/27/2024
This vulnerability resides within the boot process of Cisco Access Point software, representing a critical security flaw that undermines the device's integrity mechanisms. The issue stems from the presence of unnecessary commands that remain accessible during the boot sequence at the physical console interface. This design oversight creates an attack vector where a physically present adversary can manipulate the device's startup procedure. The vulnerability specifically targets Cisco Secure Boot functionality, which is designed to ensure that only authentic and unmodified software images can execute on the device. When an attacker interrupts the normal boot process, they can leverage these exposed commands to circumvent the validation checks that normally prevent unauthorized code execution. This represents a fundamental failure in the device's trust boundary implementation, where the boot environment lacks proper access controls and command sanitization.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables a persistent threat actor to gain unauthorized control over the device's operational capabilities. An attacker who successfully exploits this vulnerability can load a pre-downloaded malicious image that has been tampered with, effectively allowing them to execute arbitrary code on the device. The attack requires physical access to the device, which aligns with the concept of a "physical attack" as defined in the MITRE ATT&CK framework under the T1018 technique for Valid Accounts and T1059 for Command and Scripting Interpreter. However, the vulnerability's nature means that even with physical access, the attacker can bypass the device's built-in security mechanisms. The fact that the Secure Boot functionality is not permanently compromised indicates that the vulnerability exists only during the specific boot window, but this temporal window is sufficient for an attacker to establish persistent access or deploy malicious payloads. This vulnerability directly relates to CWE-284, which addresses improper access control, and CWE-311, concerning missing encryption of sensitive data, though in this case the missing security control is at the boot level rather than data encryption.
Mitigation strategies for this vulnerability must address both the immediate physical access threat and the underlying design flaw in the boot process. Organizations should implement strict physical security controls around Cisco access points, including restricted access to device console ports and proper environmental security measures to prevent unauthorized physical access. Network administrators should ensure that devices are placed in secure locations where physical tampering is minimized. Cisco has released software updates that address this vulnerability by removing the unnecessary commands from the boot process and strengthening the console access controls. The recommended remediation involves applying the latest firmware updates that contain patches for the boot process validation mechanism. Additionally, network monitoring should be enhanced to detect unusual boot patterns or unauthorized device modifications. Security teams should also consider implementing device integrity monitoring solutions that can detect when unauthorized software images are loaded onto devices. The vulnerability highlights the importance of secure boot implementation and demonstrates how even well-designed security frameworks can be undermined by implementation flaws in critical system components. Organizations should conduct regular security assessments of their network infrastructure to identify similar vulnerabilities in other network devices that may share similar boot process architectures. This vulnerability serves as a reminder of the critical importance of securing all attack surfaces, including the boot process where devices are most vulnerable to tampering.