CVE-2023-20082 - Persistent Code Execution Vulnerability in Cisco IOS XE Software for Cisco Catalyst 930 Series Switches

A critical vulnerability (CVE-2023-20082) has been discovered in Cisco IOS XE Software for Cisco Catalyst 930 Series Switches, which could enable an authenticated, local attacker with level-15 privileges or an unauthorized attacker with physical access to the device to execute persistent code at boot time and break the chain of trust. The vulnerability is due to errors that occur while retrieving the public release key used for image signature verification. A successful exploit could allow the attacker to execute persistent code on the underlying operating system.

Exploit Details

The vulnerability is caused by errors when fetching the public release key used for image signature verification. An attacker could exploit this vulnerability by modifying specific variables in the Serial Peripheral Interface (SPI) flash memory of an affected device. As a result, attackers with level-15 privileges could easily downgrade the Cisco IOS XE Software on a device to a release that would lower the attack complexity.

Code Snippet

# Example of vulnerable code

def get_public_release_key(release):
    # This function retrieves the public release key
    # to be used for image signature verification
    try:
        key = fetch_key_from_spi_flash(release)
        return key
    except KeyError:
        print("Error retrieving public release key")
        return None

# The attacker could modify specific variables in the SPI flash memory
# to exploit the vulnerability

Original References

- Cisco IOS XE Software Integrity Assurance Vulnerabilities
- Cisco Catalyst 930 Series Switches - Persistent Code Execution Vulnerability

Affected Software and Mitigations

The vulnerability affects Cisco Catalyst 930 Series Switches running Cisco IOS XE Software releases 16.11.1 and later. Cisco has released software updates to address this vulnerability. Customers are advised to upgrade to the latest software release to protect against this vulnerability.

Monitor the devices' logs for any suspicious activity or unauthorized access attempts.

- Enable strong authentication mechanisms, such as two-factor authentication, to prevent attackers from gaining level-15 privileges.

Conclusion

This vulnerability poses a significant risk to organizations using the affected Cisco Catalyst 930 Series Switches. The discovery of this vulnerability underscores the importance of keeping software up to date and implementing strong security measures to protect against potential exploitation. Organizations are advised to apply the necessary patches and follow the recommended mitigation steps to protect their critical infrastructure from potential security threats.

Timeline

Published on: 03/23/2023 17:15:00 UTC
Last modified on: 03/30/2023 20:35:00 UTC