CVE-2023-24509: Arista EOS Privilege Escalation Flaw

CVE-2023-24509 Overview

CVE-2023-24509 is a privilege escalation vulnerability affecting Arista Extensible Operating System (EOS) on modular platforms with redundant supervisor modules. When the redundancy protocol is configured with Route Processor Redundancy (RPR) or Stateful Switchover (SSO), an existing unprivileged user can log in to the standby supervisor as the root user. The flaw maps to [CWE-269: Improper Privilege Management]. Successful exploitation grants full root access to the standby supervisor, which can then be leveraged to compromise the active supervisor and the entire chassis. Valid user credentials are required to exploit this vulnerability.

Critical Impact

An authenticated low-privileged user can escalate to root on the standby supervisor of a modular Arista EOS switch, gaining full control of network infrastructure components.

Affected Products

• Arista EOS on modular platforms configured with RPR or SSO redundancy
• Arista 7300X, 7300X3, 7308X, 7316X, 7324X, 7328X series chassis
• Arista 7500R, 7500R3, 7800R3 series chassis

Discovery Timeline

• 2023-04-13 - CVE-2023-24509 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-24509

Vulnerability Analysis

The vulnerability resides in the authentication and session handling logic between the active and standby supervisor modules. Arista EOS supports redundant supervisors that synchronize state using either RPR or SSO. On affected platforms, the standby supervisor fails to enforce proper privilege boundaries when an unprivileged but authenticated user initiates a session. Instead of inheriting the user's configured role, the session is established with root-level privileges on the standby module.

Because the standby supervisor shares configuration state and file system access with the active supervisor in an SSO topology, root access on the standby provides a direct path to manipulate routing configuration, persistent storage, and credentials used by the chassis. This is classified as a local attack vector because the attacker must already hold valid credentials on the device.

Root Cause

The root cause is improper privilege management [CWE-269] in the standby supervisor login path. Authorization checks that normally enforce user role mapping on the active supervisor are not consistently applied when sessions terminate on the standby module under RPR or SSO mode.

Attack Vector

An attacker with valid unprivileged credentials authenticates to the chassis and reaches the standby supervisor through normal management interfaces. Upon successful authentication, the user receives a root shell on the standby supervisor without invoking enable or providing additional credentials. From the standby root context, the attacker can modify shared configuration state, exfiltrate cryptographic material, or stage persistent backdoors that survive failover.

No public proof-of-concept exploit is available for CVE-2023-24509, and the issue is not listed in the CISA Known Exploited Vulnerabilities catalog. Refer to Arista Security Advisory #0082 for vendor technical details.

Detection Methods for CVE-2023-24509

Indicators of Compromise

• Unexpected root shell sessions originating from non-administrative user accounts on the standby supervisor
• Configuration changes or file modifications on the standby supervisor that do not correlate with authorized administrator activity
• Authentication events for low-privileged users immediately followed by privileged command execution

Detection Strategies

• Audit AAA (Authentication, Authorization, and Accounting) logs for sessions that escalate to root without an associated enable or privilege transition event
• Compare command history and configuration deltas between active and standby supervisors to identify unauthorized changes
• Enable TACACS+ or RADIUS command accounting and forward logs to a centralized SIEM for correlation

Monitoring Recommendations

• Forward EOS syslog and AAA accounting records to a centralized logging platform for retention and analysis
• Alert on any interactive shell session on a standby supervisor that does not originate from an administrator account
• Baseline normal supervisor failover and login patterns, then alert on deviations such as repeated standby logins by unprivileged users

How to Mitigate CVE-2023-24509

Immediate Actions Required

• Upgrade Arista EOS to a fixed release as specified in Arista Security Advisory #0082
• Audit local and remote user accounts on affected chassis and remove unnecessary unprivileged accounts
• Rotate credentials and cryptographic keys that may have been exposed on chassis where the vulnerability could have been exercised

Patch Information

Arista has published fixed EOS releases in Security Advisory #0082. Operators of modular chassis running RPR or SSO redundancy should review the advisory matrix and upgrade to a remediated EOS train that corresponds to their hardware platform.

Workarounds

• Restrict management plane access to the chassis using control-plane ACLs so that only trusted administrative networks can reach the supervisors
• Use centralized AAA with strong authentication and limit account creation to administrators who require chassis access
• Where operationally feasible, run modular chassis without the RPR or SSO redundancy protocol enabled until patches are applied

# Example: restrict management access via control-plane ACL on Arista EOS
ip access-list MGMT-ACL
   10 permit tcp <trusted-mgmt-subnet>/24 any eq ssh
   20 deny ip any any log
!
management api http-commands
   no shutdown
!
control-plane
   ip access-group MGMT-ACL in