CVE-2021-21887 in PremierWave
Summary
by MITRE • 12/22/2021
A stack-based buffer overflow vulnerability exists in the Web Manager SslGenerateCSR 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.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 12/26/2021
The vulnerability identified as CVE-2021-21887 represents a critical stack-based buffer overflow within the Web Manager SSL certificate generation functionality of Lantronix PremierWave 2050 device firmware version 8.9.0.0R4. This flaw manifests specifically within the SslGenerateCSR component that handles Secure Sockets Layer certificate signing requests through the web interface. The vulnerability exists in a QEMU environment simulation, indicating it affects the actual hardware implementation as well. The flaw stems from inadequate input validation and bounds checking during the processing of HTTP requests that attempt to generate SSL certificates through the web management interface.
The technical exploitation of this vulnerability occurs through a carefully crafted HTTP request that triggers a buffer overflow condition in the stack memory region allocated for handling certificate signing requests. When an authenticated user submits a maliciously formatted request containing excessive data in specific parameters, the application fails to properly validate the input length before copying it into a fixed-size buffer. This buffer overflow allows an attacker to overwrite adjacent stack memory locations including return addresses and function pointers, potentially enabling arbitrary code execution on the target system. The vulnerability operates at the application layer and requires authentication, though the authentication mechanism itself may be bypassed through other attack vectors or the attacker may already possess valid credentials.
The operational impact of this vulnerability extends beyond simple remote code execution, as it provides attackers with full administrative control over the affected network device. The compromised system could serve as a persistent foothold for further network infiltration, allowing attackers to monitor traffic, redirect connections, or use the device as a pivot point for attacking other systems within the same network segment. The QEMU environment simulation suggests that the vulnerability affects the actual hardware implementation, making it a legitimate concern for deployed devices. This type of vulnerability aligns with CWE-121 stack-based buffer overflow classification and represents a significant risk to industrial control systems and network infrastructure devices that rely on web-based management interfaces.
Mitigation strategies for CVE-2021-21887 should prioritize immediate firmware updates from Lantronix to address the underlying buffer overflow condition. Network administrators should implement strict access controls and limit web management interface access to trusted networks only. The principle of least privilege should be enforced by ensuring that only authorized personnel possess valid authentication credentials for accessing the device's web management interface. Additional defensive measures include network segmentation to isolate critical infrastructure devices, implementing intrusion detection systems to monitor for suspicious HTTP request patterns, and conducting regular security assessments of networked devices. Organizations should also consider disabling unnecessary web management services when not actively required for device configuration and maintain comprehensive network monitoring to detect anomalous behavior indicative of exploitation attempts. The vulnerability demonstrates the importance of proper input validation and memory management practices in embedded systems and industrial network devices, aligning with ATT&CK technique T1059.007 for command and scripting interpreter execution.