CVE-2017-15134 in 389-ds-base
Summary
by MITRE
A stack buffer overflow flaw was found in the way 389-ds-base 1.3.6.x before 1.3.6.13, 1.3.7.x before 1.3.7.9, 1.4.x before 1.4.0.5 handled certain LDAP search filters. A remote, unauthenticated attacker could potentially use this flaw to make ns-slapd crash via a specially crafted LDAP request, thus resulting in denial of service.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 01/09/2020
The vulnerability identified as CVE-2017-15134 represents a critical stack buffer overflow flaw within the 389 Directory Server base implementation, specifically affecting versions prior to 1.3.6.13, 1.3.7.9, and 1.4.0.5. This issue resides in the LDAP search filter processing mechanism where the ns-slapd daemon fails to properly validate input lengths before copying data into fixed-size stack buffers. The flaw manifests when handling specially crafted LDAP requests that contain overly long or malformed search filters, creating a condition where arbitrary data can overwrite adjacent stack memory locations. The vulnerability operates at the protocol level through the Lightweight Directory Access Protocol interface, making it particularly dangerous as it requires no authentication credentials to exploit, allowing any remote attacker to trigger the condition. This represents a classic buffer overflow scenario where insufficient bounds checking permits data to exceed allocated memory boundaries, potentially leading to program termination or more severe consequences depending on the memory corruption patterns.
The technical exploitation of this vulnerability follows a well-established pattern within the context of network services and protocol implementations. When the ns-slapd process receives an LDAP search request containing a malformed filter, the parsing routine fails to enforce proper length constraints on the input data before performing memory operations. This allows an attacker to craft a request with a filter string that exceeds the predetermined buffer size, causing the stack to overflow and overwrite adjacent memory locations including return addresses and local variables. The vulnerability directly maps to CWE-121 Stack-based Buffer Overflow, which is categorized under the broader weakness of insufficient boundary checking in memory management operations. The attack vector is particularly concerning because it operates over the network without requiring authentication, making it accessible to any external party with network connectivity to the affected server. The specific nature of the flaw suggests that the implementation uses fixed-size buffers for filter processing without adequate input validation or dynamic allocation mechanisms to handle variable-length inputs.
The operational impact of CVE-2017-15134 extends beyond simple denial of service to potentially compromise the overall availability and integrity of directory services within enterprise environments. Organizations relying on 389-ds for authentication, authorization, and directory services face significant risk from this vulnerability, as successful exploitation can result in complete service disruption. The crash condition affects the core ns-slapd daemon process, which serves as the primary interface for all LDAP operations within the directory server environment, meaning that legitimate users would be unable to access directory services until the process is manually restarted or the system is rebooted. This type of vulnerability can be leveraged as part of larger attack campaigns targeting directory services, potentially serving as a stepping stone for more sophisticated attacks or as a means to establish persistent denial of service conditions. The vulnerability's impact is particularly severe in environments where directory services are critical infrastructure components, as the disruption can cascade across multiple dependent systems that rely on LDAP authentication for access control.
Mitigation strategies for CVE-2017-15134 should prioritize immediate patching of affected 389-ds installations to versions 1.3.6.13, 1.3.7.9, or 1.4.0.5 where the buffer overflow handling has been corrected. Organizations should implement network segmentation and access controls to limit exposure of directory services to untrusted networks, utilizing firewalls and access control lists to restrict LDAP traffic to authorized systems only. Additionally, monitoring and logging should be enhanced to detect anomalous LDAP search requests that might indicate exploitation attempts, including unusual filter lengths or malformed request patterns. The implementation of intrusion detection systems with signature-based detection capabilities can help identify and alert on potential exploitation attempts. From a defensive perspective, organizations should consider implementing application-level firewalls or API gateways that can perform additional input validation and sanitization before requests reach the vulnerable components. Regular security assessments and vulnerability scanning should be conducted to identify similar issues within the directory service infrastructure, as this vulnerability demonstrates the importance of proper input validation in protocol implementations. The remediation process should also include comprehensive testing to ensure that the patched version maintains all necessary functionality while eliminating the buffer overflow condition, following the principle of least privilege in directory service configurations to minimize the impact of potential future vulnerabilities.