CVE-2023-22308 in VPN
Summary
by MITRE • 10/25/2023
An integer underflow vulnerability exists in the vpnserver OvsProcessData functionality of SoftEther VPN 5.01.9674 and 5.02. A specially crafted network packet can lead to denial of service. An attacker can send a malicious packet to trigger this vulnerability.
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Analysis
by VulDB Data Team • 10/25/2023
The integer underflow vulnerability identified in CVE-2023-22308 resides within the vpnserver OvsProcessData functionality of SoftEther VPN software versions 5.01.9674 and 5.02. This flaw represents a critical security weakness that can be exploited to cause denial of service conditions within the affected network infrastructure. The vulnerability manifests when the software processes specific network packets that contain malformed data structures, particularly those related to overflow handling within the Open Virtual Switch processing components. Such vulnerabilities fall under the CWE-190 category of integer overflow/underflow, where the system fails to properly validate input parameters before performing arithmetic operations that could result in unexpected behavior.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious network packets designed to trigger an integer underflow condition within the OvsProcessData function. When the vulnerable code attempts to perform arithmetic operations on integer values that have been manipulated to exceed the minimum representable value, the system experiences undefined behavior that typically results in program termination or system instability. This type of vulnerability is particularly dangerous in network infrastructure applications like VPN servers, where sustained availability is critical for business operations and network connectivity. The attack vector requires only network access to the vulnerable server, making it relatively easy to exploit from remote locations.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it can severely disrupt network connectivity for legitimate users and potentially provide attackers with opportunities for further exploitation. When the integer underflow occurs, the affected vpnserver process may crash or become unresponsive, requiring system administrators to manually restart services and potentially causing extended downtime for users relying on the VPN infrastructure. This vulnerability directly impacts the availability aspect of the CIA triad and can be classified under the ATT&CK technique T1499.004 for network denial of service attacks. Organizations using SoftEther VPN versions 5.01.9674 and 5.02 must consider the potential for cascading failures if the VPN server serves as a critical network gateway for enterprise connectivity or remote access services.
Mitigation strategies for CVE-2023-22308 should prioritize immediate software updates to versions that have patched the integer underflow condition within the OvsProcessData functionality. Network administrators should implement robust monitoring solutions to detect unusual traffic patterns that might indicate exploitation attempts, as well as establish automated alerting for service disruptions. Additionally, implementing network segmentation and access controls can limit the potential impact of successful exploitation attempts, while maintaining detailed logging of network traffic can aid in forensic analysis should an attack occur. The vulnerability demonstrates the importance of proper input validation and bounds checking in network protocol implementations, as recommended by industry best practices for secure coding standards. Organizations should also conduct regular vulnerability assessments and penetration testing to identify similar weaknesses in their network infrastructure components that might not yet have been publicly disclosed.