CVE-2021-35394 in Jungle SDK
Summary
by MITRE • 08/16/2021
Realtek Jungle SDK version v2.x up to v3.4.14B provides a diagnostic tool called 'MP Daemon' that is usually compiled as 'UDPServer' binary. The binary is affected by multiple memory corruption vulnerabilities and an arbitrary command injection vulnerability that can be exploited by remote unauthenticated attackers.
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Analysis
by VulDB Data Team • 02/05/2025
The vulnerability identified as CVE-2021-35394 affects Realtek Jungle SDK versions v2.x through v3.4.14B, specifically targeting the diagnostic tool known as 'MP Daemon' which is typically compiled as the 'UDPServer' binary. This diagnostic utility represents a critical attack surface within Realtek's embedded networking solutions, particularly in devices that utilize Realtek's Wi-Fi and Ethernet chipsets. The MP Daemon serves as a legitimate administrative interface for device diagnostics and firmware testing, but its implementation contains multiple memory corruption flaws that fundamentally compromise system integrity and security posture.
The technical exploitation of this vulnerability stems from multiple memory corruption issues within the UDPServer binary that can be triggered through malformed network packets or improper input handling. These memory corruption flaws typically manifest as buffer overflows, use-after-free conditions, or integer overflows that allow attackers to overwrite critical memory segments and potentially execute arbitrary code. The vulnerability is particularly concerning because it affects the diagnostic tool that operates on UDP ports, making it accessible to remote unauthenticated attackers who can leverage these flaws without requiring legitimate credentials or physical access to the device. The presence of arbitrary command injection capabilities further amplifies the severity, as attackers can potentially execute system commands with the privileges of the running service.
From an operational perspective, this vulnerability creates a significant risk for any device running affected Realtek SDK versions, particularly those deployed in enterprise environments, IoT networks, or consumer devices with network connectivity. The remote unauthenticated nature of the exploit means that attackers can target these devices from anywhere on the internet, potentially leading to complete system compromise, data exfiltration, or use as a pivot point for further attacks within a network. The diagnostic tool's intended function as a development and testing interface makes it particularly dangerous when deployed in production environments, as it often remains active and accessible even when not actively used by administrators. The impact extends beyond individual device compromise to potentially affect entire network infrastructures, especially in scenarios where multiple devices share similar configurations or are managed through centralized systems.
Security mitigations for this vulnerability should begin with immediate deployment of firmware updates from Realtek and device vendors, as the primary fix involves patching the MP Daemon implementation to address the memory corruption flaws and command injection vulnerabilities. Network segmentation and firewall rules should be implemented to restrict access to the UDP ports used by the MP Daemon, particularly in production environments where this diagnostic tool is not required for normal operations. Organizations should conduct comprehensive vulnerability assessments to identify all devices running affected Realtek SDK versions and implement monitoring for suspicious network activity on the relevant UDP ports. The remediation process should also include disabling or removing the MP Daemon functionality entirely when it is not actively needed for diagnostics, as this reduces the attack surface and eliminates the risk associated with these particular vulnerabilities. This vulnerability aligns with CWE-121 for buffer overflow conditions and CWE-78 for command injection, representing a classic example of how diagnostic interfaces can become security weaknesses when not properly secured. The ATT&CK framework categorizes this vulnerability under T1210 for exploitation of remote services and T1059 for command and scripting interpreter, demonstrating how attackers can leverage such flaws to establish persistent access and execute malicious commands within compromised networks.