CVE-2021-21892 in PremierWave
Summary
by MITRE • 12/22/2021
A stack-based buffer overflow vulnerability exists in the Web Manager FsUnmount functionality of Lantronix PremierWave 2050 8.9.0.0R4 (in QEMU). A specially crafted HTTP request can lead to remote code execution. An attacker can make an authenticated HTTP request to trigger this vulnerability.
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Analysis
by VulDB Data Team • 12/26/2021
The vulnerability identified as CVE-2021-21892 represents a critical stack-based buffer overflow within the Web Manager FsUnmount functionality of Lantronix PremierWave 2050 firmware version 8.9.0.0R4. This issue manifests specifically within the QEMU emulation environment, indicating the flaw exists in the software's handling of file system unmount operations through the web interface. The vulnerability resides in the web management component that processes HTTP requests related to file system operations, making it accessible through standard network protocols. The affected device operates as a network appliance that provides web-based management capabilities, creating a direct attack surface through HTTP communications.
The technical exploitation of this vulnerability occurs through a carefully crafted HTTP request that triggers a buffer overflow condition in the stack memory region. When the web manager processes the FsUnmount function, it fails to properly validate the length of input data provided in the request parameters, allowing an attacker to exceed the allocated buffer space. This overflow enables the attacker to overwrite adjacent stack memory locations, potentially including return addresses and function pointers. The vulnerability requires authentication to exploit, as the attacker must first establish valid credentials to access the web management interface before crafting the malicious request. The stack-based nature of the overflow means that the attacker can manipulate the program's execution flow by overwriting the return address, which could lead to arbitrary code execution on the target system.
The operational impact of this vulnerability extends beyond simple privilege escalation, as successful exploitation could allow an attacker to execute arbitrary code with the privileges of the web server process. This remote code execution capability compromises the integrity and confidentiality of the entire network appliance, potentially enabling attackers to install backdoors, exfiltrate sensitive data, or establish persistent access to the network infrastructure. The vulnerability affects the device's web management interface, which typically operates with elevated privileges to perform system-level operations such as file system management. The authenticated nature of the attack means that an attacker would need to obtain valid credentials through other means, such as credential brute-forcing or social engineering attacks, before being able to leverage this specific vulnerability.
Mitigation strategies for CVE-2021-21892 should focus on immediate firmware updates from Lantronix to address the buffer overflow condition in the web management component. Network segmentation and access control measures should be implemented to restrict access to the web management interface, limiting potential attack vectors to authorized personnel only. The implementation of web application firewalls and intrusion detection systems can help monitor for suspicious HTTP requests that might indicate exploitation attempts. Security monitoring should include detection of unusual authentication patterns and abnormal web traffic to the management interface. Organizations should also consider disabling unnecessary web management services when not actively required, reducing the attack surface. The vulnerability aligns with CWE-121 stack-based buffer overflow classification and represents a significant risk under ATT&CK technique T1059.007 for command and script interpreter execution. Regular security assessments and penetration testing of network appliances should include validation of web management interface security to prevent similar vulnerabilities from persisting in operational environments.