CVE-2019-5648 in Load Balancer
Summary
by MITRE
Authenticated, administrative access to a Barracuda Load Balancer ADC running unpatched firmware <= v6.4 allows one to edit the LDAP service configuration of the balancer and change the LDAP server to an attacker-controlled system, without having to re-enter LDAP credentials. These steps can be used by any authenticated administrative user to expose the LDAP credentials configured in the LDAP connector over the network.
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Analysis
by VulDB Data Team • 04/13/2024
The vulnerability CVE-2019-5648 represents a critical authentication bypass and credential exposure flaw within Barracuda Load Balancer ADC appliances running firmware versions up to and including v6.4. This issue stems from insufficient input validation and access control mechanisms within the administrative interface, specifically affecting the LDAP service configuration management functionality. The vulnerability allows any authenticated administrative user to manipulate LDAP server settings without requiring re-authentication, creating a significant security risk for organizations relying on LDAP authentication for their load balancer management.
The technical implementation of this vulnerability resides in the improper validation of LDAP server configuration parameters within the Barracuda Load Balancer ADC administrative web interface. When an authenticated administrator attempts to modify LDAP service settings, the system fails to properly validate the target server address and does not enforce proper authentication requirements for the new LDAP server configuration. This design flaw enables attackers to redirect the LDAP service to a malicious server they control, effectively allowing them to intercept and capture the LDAP credentials that are already configured within the system. The vulnerability operates at the application layer and specifically targets the configuration management subsystem, making it particularly dangerous as it leverages existing administrative privileges.
The operational impact of CVE-2019-5648 extends beyond simple credential theft to encompass potential lateral movement and persistent access within compromised networks. Once an attacker successfully exploits this vulnerability, they can capture LDAP credentials that may be used to authenticate to various network services, potentially enabling them to escalate privileges and access additional systems within the organization's infrastructure. This vulnerability directly violates the principle of least privilege and can be categorized under CWE-284, which addresses improper access control in software applications. The attack vector requires only an authenticated administrative user account, making it particularly dangerous as it can be exploited by malicious insiders or compromised administrative accounts.
Organizations affected by this vulnerability should immediately implement mitigations including patching to firmware versions greater than v6.4, which addresses the underlying configuration validation issues. Network segmentation and monitoring should be enhanced to detect unauthorized changes to LDAP configurations, with intrusion detection systems configured to alert on unusual network connections to LDAP servers. Administrative access controls should be strengthened through multi-factor authentication implementation and regular privilege reviews. The vulnerability aligns with ATT&CK technique T1552.001, which covers "Unsecured Credentials" and T1078.002, which addresses "Valid Accounts: Domain Accounts," highlighting the importance of proper credential handling and access control measures. Additionally, organizations should conduct comprehensive security assessments to identify any potential credential exposure that may have occurred during the vulnerability's existence period.