CVE-2010-1766 in Digia
Summary
by MITRE
Off-by-one error in the WebSocketHandshake::readServerHandshake function in websockets/WebSocketHandshake.cpp in WebCore in WebKit before r56380, as used in Qt and other products, allows remote websockets servers to cause a denial of service (memory corruption) or possibly have unspecified other impact via an upgrade header that is long and invalid.
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Analysis
by VulDB Data Team • 09/20/2021
The vulnerability described in CVE-2010-1766 represents a critical off-by-one error within the WebSocket handshake processing mechanism of WebKit's WebCore component. This flaw exists in the WebSocketHandshake::readServerHandshake function located in websockets/WebSocketHandshake.cpp, specifically affecting versions prior to r56380. The vulnerability manifests when remote WebSocket servers attempt to manipulate the upgrade header during the handshake process, creating conditions that can lead to memory corruption or other unspecified impacts.
The technical nature of this vulnerability stems from improper boundary checking during the parsing of WebSocket handshake responses. An off-by-one error occurs when a program processes one element too many or too few in a sequence, leading to memory access violations. In this case, the WebSocket handshake function fails to properly validate the length of the upgrade header, allowing attackers to craft malicious headers that exceed expected boundaries. This memory corruption can occur during the parsing of server handshake responses, where the function does not adequately check buffer limits or header length constraints.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable more severe consequences including arbitrary code execution or system instability. When a remote WebSocket server sends an upgrade header that is both long and invalid, the flawed function processes this data without proper bounds checking, leading to memory corruption that can be exploited by attackers. The vulnerability affects not only the WebKit browser engine but also products that incorporate Qt's WebKit implementation, creating widespread exposure across various web applications and platforms that rely on WebSocket communication protocols.
This vulnerability aligns with CWE-129, which addresses improper validation of length of input buffers, and specifically relates to CWE-121, concerning buffer overflow conditions. The attack vector follows patterns consistent with the ATT&CK framework's T1203 technique for "Exploitation for Client Execution," where adversaries leverage vulnerabilities in client-side applications to gain unauthorized access. The flaw demonstrates how seemingly benign WebSocket protocol handling can become a critical security concern when proper input validation and memory management practices are not implemented.
Mitigation strategies for this vulnerability require immediate patching of affected WebKit versions to r56380 or later, where the off-by-one error has been corrected through proper boundary checking implementation. Organizations should also implement network-level controls such as WebSocket traffic filtering and header validation to prevent exploitation attempts. Additionally, developers should conduct thorough code reviews focusing on buffer handling and input validation in WebSocket implementations, ensuring that all header processing functions properly validate data lengths before processing. Regular security assessments of web applications utilizing WebSocket protocols are essential to identify similar vulnerabilities in custom implementations and third-party libraries.