CVE-2022-26987 in TL-WDR7660
Summary
by MITRE • 05/10/2022
TP-Link TL-WDR7660 2.0.30, Mercury D196G 20200109_2.0.4, and Fast FAC1900R 20190827_2.0.2 routers have a stack overflow issue in `MmtAtePrase` function. Local users could get remote code execution.
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Analysis
by VulDB Data Team • 05/12/2022
The vulnerability identified as CVE-2022-26987 represents a critical stack overflow condition affecting multiple router models including TP-Link TL-WDR7660 version 2.0.30, Mercury D196G with firmware 20200109_2.0.4, and Fast FAC1900R running version 20190827_2.0.2. This flaw exists within the MmtAtePrase function, which is responsible for parsing specific input parameters within the router's firmware. The stack overflow vulnerability occurs when malformed input data is processed through this function, leading to memory corruption that can be exploited by malicious actors. The vulnerability is particularly concerning because it allows local users to achieve remote code execution, meaning that an attacker who gains access to the device can potentially execute arbitrary code with elevated privileges. The affected devices operate under the assumption that input validation is sufficient, but the MmtAtePrase function fails to properly validate or sanitize the data it receives, creating a pathway for exploitation. This issue falls under CWE-121 Stack-based Buffer Overflow, which is categorized as a fundamental memory safety issue that has been consistently identified as a major threat in network device security. The vulnerability demonstrates a classic weakness in software design where insufficient input validation allows attackers to manipulate memory layout and potentially overwrite critical function pointers or return addresses. The operational impact of this vulnerability extends beyond simple unauthorized access, as successful exploitation could enable attackers to gain complete control over the affected routers, potentially allowing them to modify network configurations, redirect traffic, or establish persistent backdoors.
The technical exploitation of this vulnerability requires an attacker to send specifically crafted input data to the MmtAtePrase function, which then overflows the stack buffer and potentially allows for code execution. This type of attack aligns with ATT&CK technique T1059.007 Command and Scripting Interpreter: PowerShell, where attackers leverage device-specific vulnerabilities to execute malicious payloads. The stack overflow in this context typically involves a buffer that is allocated on the stack, and when input exceeds the allocated buffer size, it overflows into adjacent memory locations, potentially corrupting the return address or other critical program state information. The attack vector is particularly dangerous because it allows for remote code execution from within the local network, meaning that an attacker who has already gained access to the device can leverage this vulnerability to escalate privileges or install malicious software. The firmware versions mentioned in the vulnerability description are all older releases that likely lack modern security hardening features such as stack canaries, address space layout randomization, or non-executable stack protections. The vulnerability's presence in multiple vendors' products indicates a common codebase or shared development practices that may have introduced the same flaw across different device models. Network administrators should be aware that this vulnerability is not limited to a single vendor but affects a range of consumer and enterprise networking equipment, making it a widespread concern for network security professionals.
Mitigation strategies for CVE-2022-26987 should prioritize immediate firmware updates from the affected vendors, as these updates typically include patches that address the stack overflow condition in the MmtAtePrase function. Organizations should implement network segmentation to limit the potential impact of exploitation, particularly by isolating critical network segments from devices that may be vulnerable. Access controls should be strengthened through the implementation of secure authentication mechanisms and regular monitoring of network traffic for suspicious activity patterns that may indicate exploitation attempts. The vulnerability highlights the importance of input validation and proper memory management in embedded systems, and organizations should consider implementing additional security measures such as intrusion detection systems that can monitor for anomalous behavior patterns associated with buffer overflow exploitation. Security teams should also consider deploying network-based firewalls or access control lists to restrict communication with vulnerable devices and limit potential attack surface. The remediation process should include thorough testing of firmware updates in controlled environments before deployment to ensure that patches do not introduce compatibility issues with existing network configurations. Additionally, regular vulnerability assessments should be conducted to identify similar weaknesses in other network infrastructure components, as this vulnerability demonstrates how seemingly minor implementation flaws can lead to significant security risks. Organizations should also consider implementing network monitoring solutions that can detect potential exploitation attempts and provide alerts when suspicious activities are observed, particularly in relation to network devices that may be vulnerable to similar stack overflow conditions.