CVE-2018-1140 in Samba
Summary
by MITRE
A missing input sanitization flaw was found in the implementation of LDP database used for the LDAP server. An attacker could use this flaw to cause a denial of service against a samba server, used as a Active Directory Domain Controller. All versions of Samba from 4.8.0 onwards are vulnerable
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Analysis
by VulDB Data Team • 03/17/2020
The vulnerability identified as CVE-2018-1140 represents a critical security flaw in the Lightweight Directory Access Protocol database implementation within Samba server software. This issue specifically affects the LDAP database handling mechanism that Samba employs when functioning as an Active Directory Domain Controller. The flaw stems from inadequate input sanitization processes that fail to properly validate and sanitize user-supplied data before processing it within the LDP database subsystem. This missing validation step creates a pathway for malicious actors to exploit the system through carefully crafted input sequences that can trigger unexpected behavior in the underlying database operations.
The technical nature of this vulnerability aligns with CWE-20, which describes improper input validation, and demonstrates how insufficient sanitization can lead to cascading system failures. When an attacker submits maliciously formatted data to the LDAP database through the Samba server, the system processes this input without adequate filtering mechanisms, potentially causing the database operations to enter unstable states or crash entirely. The vulnerability specifically impacts all Samba versions beginning with 4.8.0, indicating that the flaw was introduced or became exploitable within this release cycle, making it particularly concerning for organizations that have upgraded to these newer versions.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire Active Directory infrastructure that relies on Samba as a domain controller. A successful exploitation can result in sustained denial of service conditions that prevent legitimate users from accessing directory services, authenticating to domain resources, or performing essential administrative functions. This type of attack can have severe implications for enterprise environments where Samba serves as a critical component of the authentication infrastructure, potentially affecting thousands of users and disrupting business operations across multiple departments and systems.
Organizations affected by this vulnerability should prioritize immediate remediation through official Samba security updates that address the input sanitization deficiencies in the LDAP database implementation. System administrators should also implement network-level monitoring to detect suspicious LDAP traffic patterns that might indicate exploitation attempts. The mitigation strategy should include not only patching the vulnerable software but also establishing robust input validation controls and implementing intrusion detection systems that can identify anomalous database access patterns. Additionally, organizations should consider implementing network segmentation and access controls to limit the potential impact of successful exploitation attempts, as outlined in the attack techniques documented in the MITRE ATT&CK framework under the T1489 category for unauthorized data access and denial of service operations.