Cisco has updated this alert to correct the attribution of thanks to the reporter of this vulnerability, as well as to assign a CVE name.
Cisco Linksys WRT54GC firmware versions prior to 1.06.1 contain a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.
The vulnerability is due to insufficient boundary restrictions on strings in HTTP POST requests processed by the device's web-based management interface. An unauthenticated, remote attacker could exploit the vulnerability by sending malicious HTTP requests to the device. If successful, the attacker could cause the device to stop responding, resulting in a DoS condition.
Exploit code is available.
Cisco confirmed the vulnerability and released firmware updates.
Cisco Linksys WRT54GC firmware versions prior to 1.06.1 are vulnerable.
To exploit the vulnerability, the attacker must be able to send malicious HTTP requests to the device on an internal interface. The attacker may require access to internal networks to accomplish this goal, making exploitation more difficult.
Exploit code that results in a DoS condition is available. Although theoretically possible with a buffer overflow vulnerability of this type, code execution has not been proven in available technical details or exploit code.
Cisco thanks Yuji Ukai of Fourteenforty Research Institute, Inc. for reporting this vulnerability.
An unauthenticated, remote attacker could exploit this vulnerability to cause a targeted device to stop responding, resulting in a DoS condition.
The vulnerability is due to insufficient boundary restrictions on strings in HTTP POST requests processed by the device's web-based management interface.
An unauthenticated, remote attacker could exploit the vulnerability by sending malicious HTTP POST requests that contain overly large string values to the device. When processed, the request could cause a buffer overflow condition. The resulting memory error may cause the device to stop responding, resulting in a DoS condition.
Administrators are advised to apply the available firmware updates.
Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
Administrators are advised to monitor critical systems.
Version 1, January 13, 2011, 4:24 PM: Cisco Linksys WRT54GC devices contain a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available.
The security vulnerability applies to the following combinations of products.
WRT54GC Router Firmware (Version 1.0)
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