CVE-2024-21440 Overview
CVE-2024-21440 is a remote code execution vulnerability in the Microsoft Open Database Connectivity (ODBC) Driver. The flaw affects supported versions of Windows 10, Windows 11, and Windows Server. Microsoft published the advisory on March 12, 2024 as part of its monthly Patch Tuesday release.
An attacker can exploit this vulnerability over the network when a user interacts with a malicious application or connection that calls the affected ODBC driver. Successful exploitation grants the attacker the ability to execute arbitrary code in the context of the targeted process. The associated weakness is CWE-197 (Numeric Truncation Error).
Critical Impact
Successful exploitation allows remote attackers to execute arbitrary code on affected Windows systems, leading to full compromise of confidentiality, integrity, and availability.
Affected Products
- Microsoft Windows 10 (versions 1507, 1607, 1809, 21H2, 22H2)
- Microsoft Windows 11 (versions 21H2, 22H2, 23H2)
- Microsoft Windows Server 2008, 2012, 2016, 2019, 2022, and 2022 23H2
Discovery Timeline
- 2024-03-12 - Microsoft releases security patch and advisory for CVE-2024-21440
- 2024-03-12 - CVE-2024-21440 published to the National Vulnerability Database (NVD)
- 2024-12-05 - Last updated in NVD database
Technical Details for CVE-2024-21440
Vulnerability Analysis
The vulnerability resides in the Microsoft ODBC Driver, a system component that allows applications to communicate with database management systems using a standardized API. A flaw in how the driver processes data values enables an attacker to trigger code execution within the calling process.
The weakness is classified as CWE-197 (Numeric Truncation Error), which occurs when a value of a larger numeric type is converted to a smaller type without proper validation. The truncation can produce unexpected values that bypass length checks, leading to memory corruption or incorrect control flow inside the driver.
Exploitation requires user interaction. A user must connect to an attacker-controlled database server or open a malicious file that invokes the vulnerable ODBC code path.
Root Cause
The root cause is improper handling of numeric conversions within the ODBC Driver. When the driver narrows a wide integer to a smaller type during data processing, the truncated value can misrepresent buffer sizes or offsets. The driver then operates on memory using these incorrect values, creating an exploitable condition.
Attack Vector
The attack is network-based and requires user interaction. A typical scenario involves an attacker hosting a malicious SQL Server or other database endpoint. When a victim application uses the Microsoft ODBC Driver to connect to that endpoint, the server returns crafted responses that trigger the truncation flaw. Code then executes within the privilege context of the client process.
No verified public proof-of-concept exploit code is available. Microsoft has not reported observed exploitation in the wild, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.
Detection Methods for CVE-2024-21440
Indicators of Compromise
- Unexpected outbound connections from applications using ODBC (sqlsrv32.dll, msodbcsql*.dll) to untrusted database endpoints on TCP/1433 or alternate ports.
- Child processes spawned by applications that normally only perform database queries (for example, Office or LOB applications launching cmd.exe or powershell.exe).
- Crash events or anomalous memory access faults in processes loading the Microsoft ODBC Driver.
Detection Strategies
- Hunt for ODBC client processes establishing connections to external or untrusted IP addresses that do not match the organization's database inventory.
- Inspect Windows Event Logs and Application Error logs for crashes in modules associated with ODBC drivers.
- Correlate process creation events with module load events to identify suspicious code execution following an ODBC session.
Monitoring Recommendations
- Baseline normal ODBC client-to-server communication patterns and alert on deviations.
- Monitor endpoint telemetry for module loads of msodbcsql17.dll, msodbcsql18.dll, and related ODBC components by non-standard applications.
- Track patch deployment status for the March 2024 Microsoft security updates across the Windows estate.
How to Mitigate CVE-2024-21440
Immediate Actions Required
- Apply the March 2024 Microsoft security updates referenced in the Microsoft CVE-2024-21440 Update Guide to all affected Windows and Windows Server systems.
- Inventory applications that rely on the Microsoft ODBC Driver and prioritize patching on hosts where users initiate outbound database connections.
- Restrict outbound traffic to known, trusted database servers to reduce exposure to attacker-controlled endpoints.
Patch Information
Microsoft released security updates for all affected Windows 10, Windows 11, and Windows Server versions on March 12, 2024. Refer to the Microsoft CVE-2024-21440 Update Guide for the specific KB articles applicable to each Windows build.
Workarounds
- Block outbound TCP/1433 and other database ports at the perimeter for endpoints that do not require external database connectivity.
- Enforce application allowlisting to prevent users from launching untrusted applications that may load the vulnerable ODBC driver.
- Educate users on the risks of connecting to untrusted database servers or opening unsolicited .udl, .dsn, or office documents containing external data connections.
# Verify installation status of the March 2024 cumulative update on Windows
wmic qfe list brief /format:table
# Example: block outbound SQL Server traffic from non-server endpoints
New-NetFirewallRule -DisplayName "Block Outbound SQL 1433" -Direction Outbound -Protocol TCP -RemotePort 1433 -Action Block
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
