CVE-2022-46377 in Weston uC-FTPs v
Summary
by MITRE • 05/10/2023
An out-of-bounds read vulnerability exists in the PORT command parameter extraction functionality of Weston Embedded uC-FTPs v 1.98.00. A specially-crafted set of network packets can lead to denial of service. An attacker can send packets to trigger this vulnerability.This vulnerability occurs when no IP address argument is provided to the `PORT` command.
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Analysis
by VulDB Data Team • 06/02/2023
The vulnerability described in CVE-2022-46377 represents a critical out-of-bounds read condition within the Weston Embedded uC-FTPs v1.98.00 FTP server implementation. This flaw specifically manifests in the parameter extraction functionality of the PORT command, which is a standard FTP command used to specify the IP address and port number that the server should connect to for data transfer. The vulnerability arises from inadequate input validation and boundary checking when processing FTP commands, creating a scenario where the software attempts to access memory locations beyond the allocated buffer boundaries.
The technical nature of this vulnerability stems from the absence of proper validation when handling the PORT command without an IP address argument. When an attacker sends a malformed FTP PORT command that omits the required IP address parameter, the uC-FTPs software fails to properly validate the input before attempting to parse and extract the parameters. This results in the application reading memory beyond the intended data structures, potentially accessing invalid memory locations that could contain sensitive information or cause the application to crash. The vulnerability is classified as an out-of-bounds read according to CWE-129, which specifically addresses issues related to improper validation of the length or index of data structures.
From an operational perspective, this vulnerability creates a significant denial of service risk for systems running the affected uC-FTPs version. An attacker can reliably trigger this condition by sending a specially crafted network packet containing a PORT command without the required IP address argument, causing the FTP server to crash or become unresponsive. The impact extends beyond simple service disruption as the out-of-bounds memory access could potentially expose sensitive data from the server's memory space or allow for more sophisticated exploitation techniques. This vulnerability directly maps to the ATT&CK technique T1499.004, which covers the use of denial of service attacks against network services, and represents a classic example of how improper input validation can lead to system instability.
The mitigation strategy for this vulnerability requires immediate patching of the uC-FTPs software to version 1.99.00 or later, which contains the necessary fixes for proper input validation. System administrators should also implement network-level protections such as firewall rules that restrict FTP traffic to trusted sources and monitor for suspicious PORT command patterns. Additionally, implementing intrusion detection systems that can identify malformed FTP commands and deploying application-level firewalls that can filter out malicious packets before they reach the FTP server are recommended defensive measures. Organizations should also conduct thorough security testing to ensure that similar input validation issues do not exist in other components of their network infrastructure, as this vulnerability demonstrates the importance of robust parameter validation in network services. The fix implemented in the patched version addresses the root cause by adding proper boundary checks and input validation before any parameter extraction occurs, preventing the out-of-bounds memory access condition that previously led to system instability.