CVE-2024-37320: Microsoft SQL Server 2016 RCE Vulnerability

CVE-2024-37320 Overview

CVE-2024-37320 is a remote code execution vulnerability in the Microsoft SQL Server Native Client OLE DB Provider. The flaw is rooted in a use-after-free condition [CWE-416] within the OLE DB provider component that handles client connections to SQL Server instances. Successful exploitation allows an attacker to execute arbitrary code in the context of the affected client process.

The vulnerability affects SQL Server 2016, 2017, 2019, and 2022. Exploitation requires user interaction, typically by inducing a victim to connect to a malicious SQL Server or process a crafted response. Microsoft disclosed the issue and released fixes through the July 2024 Patch Tuesday cycle.

Critical Impact

An attacker who successfully exploits CVE-2024-37320 can execute arbitrary code on the target system with the privileges of the user running the OLE DB client, leading to full compromise of confidentiality, integrity, and availability.

Affected Products

• Microsoft SQL Server 2016
• Microsoft SQL Server 2017
• Microsoft SQL Server 2019
• Microsoft SQL Server 2022

Discovery Timeline

• 2024-07-09 - CVE-2024-37320 published to NVD by Microsoft
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-37320

Vulnerability Analysis

The vulnerability resides in the SQL Server Native Client OLE DB Provider, the legacy data-access component used by applications to communicate with SQL Server. The defect is classified as a use-after-free [CWE-416], meaning the provider continues to access memory that has already been released back to the heap.

When a client establishes or processes a connection to a remote SQL Server, the OLE DB provider parses server-supplied data structures. Improper lifetime management of these objects allows a dangling pointer to be dereferenced. An attacker who controls the server response can groom the heap to place attacker-controlled data into the freed allocation.

Because OLE DB providers run in-process with the calling application, code execution occurs at the privilege level of that host application. This routinely includes interactive user contexts and, in some deployments, service accounts with elevated rights on database tooling.

Root Cause

The root cause is improper object lifecycle handling inside the Native Client OLE DB Provider. A reference to a freed memory region is reused during connection or query processing, enabling memory corruption when the freed allocation is reclaimed with attacker-influenced content.

Attack Vector

Exploitation is network-based but requires user interaction. A common scenario involves persuading a user to connect from a vulnerable client tool to a malicious SQL Server endpoint controlled by the attacker. The hostile server returns a crafted protocol response that triggers the use-after-free in the client OLE DB provider, after which the attacker pivots the corrupted state into arbitrary code execution. No prior authentication to the malicious server is required.

No verified public proof-of-concept code is available for CVE-2024-37320. Refer to the Microsoft CVE-2024-37320 Advisory for vendor technical details.

Detection Methods for CVE-2024-37320

Indicators of Compromise

• Unexpected outbound TDS (TCP/1433 or configured SQL ports) connections from workstations, BI tools, or developer endpoints to untrusted external hosts.
• Crashes or abnormal terminations in processes loading sqlncli11.dll or msoledbsql.dll, especially with Windows Error Reporting entries referencing heap corruption.
• Spawning of cmd.exe, powershell.exe, or rundll32.exe as child processes of applications that host the OLE DB provider (for example, Excel, SSMS, or custom line-of-business apps).

Detection Strategies

• Hunt for module loads of the SQL Server Native Client OLE DB Provider DLLs followed by suspicious child process creation or memory allocations marked as executable.
• Correlate process crashes in OLE DB consumers with outbound database protocol traffic to non-corporate IP space.
• Inspect EDR telemetry for patterns consistent with heap grooming and shellcode execution inside Office, SSMS, or .NET host processes that consume OLE DB.

Monitoring Recommendations

• Enable Windows Defender Exploit Guard or equivalent exploit mitigation logging on hosts running SQL client tooling.
• Forward Sysmon Event IDs 1, 7, and 10 to a centralized analytics platform to track module loads and process access against OLE DB DLLs.
• Restrict and log egress to TCP/1433 and SQL Browser UDP/1434 so that connections to unknown external endpoints are surfaced for review.

How to Mitigate CVE-2024-37320

Immediate Actions Required

• Apply Microsoft's July 2024 SQL Server cumulative updates to all affected SQL Server 2016, 2017, 2019, and 2022 instances, plus standalone deployments of the Native Client.
• Inventory endpoints that still rely on the deprecated SQL Server Native Client (sqlncli) and prioritize migration to the supported Microsoft OLE DB Driver for SQL Server (MSOLEDBSQL).
• Block outbound SQL Server protocol traffic from user workstations to untrusted networks at the perimeter firewall.

Patch Information

Microsoft published patches alongside the July 2024 security release. Refer to the Microsoft CVE-2024-37320 Advisory for the exact build numbers and KB articles that correspond to each affected SQL Server version. Patches must be applied to both server installations and client redistributables that ship the vulnerable OLE DB provider.

Workarounds

• Until patches are deployed, restrict client applications so they only connect to known internal SQL Server instances using allow-listed hostnames and IPs.
• Remove or disable the legacy SQL Server Native Client on systems that can be migrated to the modern MSOLEDBSQL driver.
• Train users with database tooling (SSMS, Excel, Power BI Desktop) to avoid opening connection files or links received from untrusted sources.

# Configuration example: enumerate hosts with the legacy Native Client installed
Get-WmiObject -Class Win32_Product | \
  Where-Object { $_.Name -like 'Microsoft SQL Server*Native Client*' } | \
  Select-Object Name, Version, InstallDate