CVE-2024-1488 in Unbound
Summary
by MITRE • 02/15/2024
A vulnerability was found in Unbound due to incorrect default permissions, allowing any process outside the unbound group to modify the unbound runtime configuration. If a process can connect over localhost to port 8953, it can alter the configuration of unbound.service. This flaw allows an unprivileged attacker to manipulate a running instance, potentially altering forwarders, allowing them to track all queries forwarded by the local resolver, and, in some cases, disrupting resolving altogether.
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Analysis
by VulDB Data Team • 01/24/2025
The vulnerability identified as CVE-2024-1488 represents a critical security flaw in the Unbound DNS resolver implementation that stems from improper default permission settings. This issue affects the core security model of the DNS resolver service by creating an unauthorized modification pathway that undermines the integrity of the runtime configuration. The flaw specifically targets the default configuration permissions that should restrict access to the unbound service's operational parameters, creating a scenario where external processes can manipulate the resolver's behavior without proper authorization.
The technical nature of this vulnerability lies in the incorrect default file and socket permissions that govern access to the Unbound service's configuration interface. When a process can establish a localhost connection to port 8953, which serves as the default control port for Unbound's command interface, it gains the ability to send configuration commands that alter the resolver's operational parameters. This represents a fundamental breakdown in the principle of least privilege, as the default configuration does not properly isolate the control interface from unauthorized access. The vulnerability manifests through the service's failure to implement proper authentication mechanisms or access controls on its control port, allowing any process with network connectivity to the localhost interface to issue configuration changes.
The operational impact of CVE-2024-1488 extends beyond simple configuration modification, creating a significant attack surface that can be exploited by unprivileged attackers to gain persistent control over DNS resolution behavior. An attacker who can establish a connection to port 8953 can manipulate forwarder settings, potentially redirecting DNS queries to malicious servers or establishing surveillance capabilities that allow them to track all queries forwarded by the local resolver. This capability enables man-in-the-middle attacks where the attacker can intercept and potentially modify DNS responses, creating a vector for data exfiltration, malicious redirection, or complete disruption of the DNS resolution service. The vulnerability's impact is particularly severe because it allows attackers to compromise the integrity of the entire DNS resolution infrastructure on a compromised system.
This vulnerability aligns with CWE-276, which addresses improper permissions for critical resources, and represents a classic case of insufficient access control. The flaw demonstrates how default configurations can create security weaknesses when they fail to properly isolate service interfaces from unauthorized access. From an ATT&CK perspective, this vulnerability maps to T1059.007 for command and scripting interpreter and T1566 for credential access through service manipulation. The attack vector involves establishing network connectivity to the localhost interface and leveraging the service's control protocol to issue configuration commands, representing a sophisticated approach to privilege escalation and service manipulation.
Organizations should implement immediate mitigations including configuring proper access controls on port 8953, restricting network access to the control interface, and ensuring that only authorized processes can establish connections to the Unbound service's control port. The recommended approach involves implementing proper firewall rules, configuring the service to bind only to specific interfaces, and ensuring that the control interface requires authentication before allowing configuration changes. Additionally, administrators should consider disabling the control interface entirely if it is not required for operational purposes, and regularly audit access permissions to prevent unauthorized processes from gaining access to the service's configuration interface. These measures align with security best practices for service hardening and help prevent the exploitation of similar permission-based vulnerabilities in network services.