CVE-2016-7253 in SQL Server
Summary
by MITRE
The agent in Microsoft SQL Server 2012 SP2, 2012 SP3, 2014 SP1, 2014 SP2, and 2016 does not properly check the atxcore.dll ACL, which allows remote authenticated users to gain privileges via unspecified vectors, aka "SQL Server Agent Elevation of Privilege Vulnerability."
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Analysis
by VulDB Data Team • 09/30/2022
The vulnerability identified as CVE-2016-7253 represents a critical privilege escalation flaw within Microsoft SQL Server Agent components across multiple versions including 2012 SP2, 2012 SP3, 2014 SP1, 2014 SP2, and 2016. This weakness specifically targets the agent's handling of access control lists for the atxcore.dll dynamic link library, creating an avenue for authenticated attackers to elevate their privileges within the database environment. The vulnerability falls under the category of improper access control as classified by CWE-284, where the system fails to properly enforce access restrictions on critical system components. The SQL Server Agent service operates with elevated privileges to perform administrative tasks, making it a prime target for privilege escalation attacks that could potentially compromise the entire database infrastructure.
The technical implementation of this vulnerability stems from the agent's failure to properly validate the access control list associated with atxcore.dll, which serves as a core component in SQL Server Agent operations. This flaw allows authenticated users to manipulate the security context of the agent service, potentially enabling them to execute arbitrary code with elevated privileges. The unspecified vectors mentioned in the vulnerability description suggest that attackers could leverage various attack surfaces including but not limited to job scheduling, remote procedure calls, or other agent-specific interfaces to exploit this weakness. The vulnerability demonstrates a classic security misconfiguration where the system fails to enforce proper authorization checks on critical system libraries, creating a pathway for privilege escalation attacks that align with ATT&CK technique T1068.
The operational impact of CVE-2016-7253 extends beyond simple privilege escalation, potentially enabling attackers to gain full control over database servers and access sensitive information. An attacker who successfully exploits this vulnerability could execute malicious code with system-level privileges, modify database contents, extract confidential data, or establish persistent access to the compromised environment. The vulnerability affects organizations running multiple SQL Server versions, making it particularly concerning for enterprise environments where database administrators often maintain elevated privileges to manage database operations. This weakness could be exploited by attackers who have already gained access to a legitimate user account within the SQL Server environment, turning a standard user account into a system administrator level privilege.
Mitigation strategies for this vulnerability should focus on immediate patching of affected SQL Server versions, implementing the latest security updates from Microsoft, and applying the security advisory recommendations provided by the vendor. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of such vulnerabilities. The principle of least privilege should be enforced by ensuring that SQL Server Agent accounts operate with minimal required permissions, and that access to database servers is restricted to authorized personnel only. Additionally, monitoring and logging of SQL Server Agent activities should be enhanced to detect potential exploitation attempts, as the vulnerability could be used to establish persistent backdoors within the database environment. Organizations should also review their overall security posture and implement defense-in-depth strategies to protect against similar access control weaknesses that could be exploited through different attack vectors.