CVE-2024-26200: Windows RRAS RCE Vulnerability Explained

CVE-2024-26200 Overview

CVE-2024-26200 is a remote code execution vulnerability in the Windows Routing and Remote Access Service (RRAS). The flaw stems from a heap-based buffer overflow [CWE-122] in the RRAS component. Attackers can exploit it over the network when a user interacts with a crafted resource, leading to arbitrary code execution in the context of the RRAS service.

Microsoft published the advisory on April 9, 2024. The vulnerability affects a broad range of Windows client and server releases where the RRAS role is enabled. RRAS is not installed by default, but environments running site-to-site VPNs, dial-up access, or software routing are exposed.

Critical Impact

Successful exploitation grants attackers remote code execution on Windows hosts running the RRAS role, enabling lateral movement, credential theft, and full system compromise.

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 Server 2022 23H2

Discovery Timeline

• 2024-04-09 - CVE-2024-26200 published to NVD and Microsoft releases security update
• 2025-01-08 - Last updated in NVD database

Technical Details for CVE-2024-26200

Vulnerability Analysis

The vulnerability resides in the Windows Routing and Remote Access Service, a server role that provides routing, dial-up remote access, and VPN services. The defect is classified as a heap-based buffer overflow [CWE-122], where input data exceeds the bounds of a heap-allocated buffer during RRAS request handling.

Exploitation requires the target system to run the RRAS role and a user to interact with attacker-supplied content. The attack vector is network-based and requires no prior authentication. On success, the attacker executes code within the privileged context of the RRAS service.

The EPSS probability for this CVE is 2.98% with a percentile of 86.7, indicating elevated relative likelihood of exploitation attempts compared to most published CVEs.

Root Cause

The root cause is improper validation of input length or structure within an RRAS message parser. When the service processes a malformed request, the heap buffer overflow corrupts adjacent memory structures. Attackers shape the overflow contents to redirect execution flow or pivot via function pointers reachable from the corrupted heap region.

Attack Vector

Attackers deliver a crafted request to a Windows host running RRAS. The vulnerability requires user interaction, meaning a user must trigger an action such as connecting to an attacker-controlled resource or processing attacker-supplied input that the RRAS service handles. After the overflow corrupts the heap, the attacker gains code execution under the RRAS service account.

For technical details, see the Microsoft Security Update CVE-2024-26200 advisory. No public proof-of-concept code or in-the-wild exploitation has been confirmed.

Detection Methods for CVE-2024-26200

Indicators of Compromise

• Unexpected child processes spawned by svchost.exe hosting the RemoteAccess service, particularly command interpreters such as cmd.exe or powershell.exe
• Crash events or Windows Error Reporting entries referencing RRAS service binaries (rasmans.dll, mprdim.dll)
• Outbound network connections initiated by the RRAS service to non-corporate destinations
• New scheduled tasks, services, or local accounts created shortly after RRAS activity spikes

Detection Strategies

• Inventory all hosts where the Routing and Remote Access role is installed and enabled, then prioritize them for behavioral monitoring
• Alert on anomalous process trees descending from the RRAS service host, including any LOLBins executed in that lineage
• Monitor for memory access violations and service crashes affecting RRAS components, which may indicate exploitation attempts

Monitoring Recommendations

• Enable Windows Event Log forwarding for System and Security channels from all RRAS servers to a central SIEM
• Capture endpoint telemetry on process creation (Event ID 4688 or Sysmon Event ID 1) for RRAS service hosts
• Track inbound network flows to RRAS-listening ports and correlate with subsequent service crashes or child process activity

How to Mitigate CVE-2024-26200

Immediate Actions Required

• Apply the Microsoft April 2024 security update referenced in the MSRC advisory to all affected Windows client and server versions
• Identify systems with the RRAS role enabled and prioritize them for immediate patching
• Restrict inbound network access to RRAS services using host firewalls and network segmentation until patching completes
• Audit RRAS service accounts and rotate credentials if exploitation is suspected

Patch Information

Microsoft released fixes through the April 2024 Patch Tuesday cycle. Refer to the Microsoft Security Update CVE-2024-26200 advisory for the specific KB articles applicable to each Windows version and install the corresponding cumulative update.

Workarounds

• Disable the Routing and Remote Access service on systems that do not require routing, dial-up, or VPN functionality
• Block external access to RRAS-related ports at the perimeter firewall to limit network reachability
• Apply the principle of least privilege to user accounts that interact with RRAS-managed connections

# Disable the Routing and Remote Access service where not required (PowerShell, run as Administrator)
Stop-Service -Name RemoteAccess -Force
Set-Service -Name RemoteAccess -StartupType Disabled

# Verify current state
Get-Service -Name RemoteAccess | Select-Object Name, Status, StartType