CVE-2021-35977 in RealPort
Summary
by MITRE • 10/08/2021
An issue was discovered in Digi RealPort for Windows through 4.8.488.0. A buffer overflow exists in the handling of ADDP discovery response messages. This could result in arbitrary code execution.
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Analysis
by VulDB Data Team • 10/14/2021
The vulnerability identified as CVE-2021-35977 resides within Digi RealPort for Windows software version 4.8.488.0 and earlier, representing a critical buffer overflow flaw in the ADDP discovery response message handling mechanism. This issue manifests when the software processes incoming discovery messages, specifically those formatted according to the ADDP protocol used for device discovery in serial communication networks. The buffer overflow vulnerability occurs due to insufficient input validation and bounds checking within the software's message parsing routines, creating a potential execution path where maliciously crafted discovery responses could trigger memory corruption. The flaw falls under the CWE-121 category of Stack-based Buffer Overflow, where insufficient bounds checking allows an attacker to write beyond the allocated buffer boundaries and overwrite adjacent memory locations.
The operational impact of this vulnerability extends significantly within environments that rely on Digi RealPort for Windows for serial port management and device communication. Attackers exploiting this buffer overflow could potentially execute arbitrary code with the privileges of the affected application process, which typically runs with elevated permissions due to the nature of serial port management software. This could lead to complete system compromise, allowing threat actors to establish persistent access, escalate privileges, or deploy additional malware within the network infrastructure. The vulnerability is particularly concerning in industrial control systems and enterprise environments where serial communication devices are prevalent and where the software may be running on critical infrastructure components. The attack surface is broad as the ADDP discovery protocol is commonly used for network device enumeration and communication setup.
Mitigation strategies for CVE-2021-35977 should prioritize immediate software updates from Digi to address the buffer overflow in the ADDP handling code. Organizations should implement network segmentation and access controls to limit exposure of affected systems to untrusted networks or devices that could send malicious discovery responses. Network monitoring should be enhanced to detect anomalous ADDP discovery traffic patterns that might indicate exploitation attempts. Security teams should also consider disabling unnecessary discovery protocols when not required for operations, and implement proper input validation at network boundaries to filter malformed discovery responses. From an ATT&CK framework perspective, this vulnerability maps to technique T1059.007 for command and script interpreter execution, potentially enabling lateral movement through T1021.002 remote services, and privilege escalation via T1068 local privilege escalation. The vulnerability demonstrates the importance of secure coding practices and input validation in network protocol implementations, particularly for software handling serial communication protocols where the attack surface includes both network and system-level privileges. Organizations should also conduct vulnerability assessments to identify other components that might be similarly vulnerable to buffer overflow conditions in their serial communication infrastructure.