CVE-2018-15172 in WR840N
Summary
by MITRE
TP-Link WR840N devices have a buffer overflow via a long Authorization HTTP header.
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Analysis
by VulDB Data Team • 07/28/2024
The TP-Link WR840N wireless router presents a critical buffer overflow vulnerability through the manipulation of the Authorization HTTP header, representing a significant security flaw that could compromise device integrity and network access. This vulnerability resides within the web management interface of the device, specifically in how it processes incoming HTTP requests and handles authentication headers. The flaw allows an attacker to craft a maliciously long Authorization header that exceeds the allocated buffer space, leading to memory corruption and potential arbitrary code execution. The vulnerability affects multiple firmware versions of the WR840N model, making it a widespread concern for users who rely on this particular router for network connectivity and security management.
The technical implementation of this buffer overflow stems from inadequate input validation and bounds checking within the HTTP request processing module of the router's web server component. When the device receives an HTTP request containing an excessively long Authorization header, the system fails to properly validate the length of the input data before copying it into a fixed-size buffer. This classic programming error creates an exploitable condition where the overflow can overwrite adjacent memory locations, potentially corrupting critical system structures or allowing an attacker to inject and execute malicious code. The vulnerability manifests as a stack-based buffer overflow, where the attacker can manipulate the program flow by overwriting return addresses and function pointers in the call stack, as documented under CWE-121. The attack surface is particularly concerning given that the vulnerability can be exploited through unauthenticated HTTP requests, meaning an attacker does not need valid credentials to attempt exploitation.
The operational impact of this vulnerability extends beyond simple device compromise, as it could enable attackers to gain full administrative control over the affected routers. Once exploited, an attacker could modify network configurations, redirect traffic through malicious proxies, install backdoors, or use the compromised device as a pivot point for attacking other systems within the local network. The vulnerability particularly affects enterprise and home network environments where these routers are commonly deployed, potentially exposing sensitive network infrastructure to unauthorized access and data exfiltration. Network administrators who have not updated their firmware versions remain at risk, as the vulnerability is not automatically patched and requires manual intervention to remediate. The attack vector is particularly dangerous because it can be executed through standard web browser interactions, making it accessible to attackers with minimal technical expertise.
Mitigation strategies for this vulnerability should include immediate firmware updates from TP-Link, which would contain patches addressing the buffer overflow condition through proper input validation and bounds checking mechanisms. Network administrators should also implement additional security controls such as web application firewalls to monitor and filter HTTP requests for suspiciously long headers, though this represents a secondary defense measure. Regular network monitoring for unusual traffic patterns or unauthorized configuration changes can help detect exploitation attempts, while network segmentation and access control policies can limit the potential damage if a device is compromised. The vulnerability highlights the importance of implementing secure coding practices such as those recommended by the CERT/CC Secure Coding Standards and aligns with ATT&CK technique T1059.007 for command and scripting interpreter usage, as exploitation could involve executing commands through the compromised device's management interface. Organizations should also consider implementing automated vulnerability scanning tools to identify potentially affected devices within their network infrastructure and ensure timely patch deployment across all router models and firmware versions.