Cisco Firewall Services Module (FWSM) contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.
The vulnerability is due to improper URL handling by the affected software when processing client requests via the auth-proxy feature. An unauthenticated, remote attacker could exploit the vulnerability by submitting crafted URLs to a targeted device running the software. A successful exploit could allow the attacker to cause a DoS condition for legitimate users.
Cisco has confirmed the vulnerability in a security advisory and has released software updates.
Indicators of Compromise
Cisco FWSM Software versions 3.1, 3.2, 4.0, and 4.1 are affected.
The vulnerability is due to improper URL handling when processing client requests via the auth-proxy feature of the affected software.
An unauthenticated, remote attacker could exploit the vulnerability by submitting crafted URLs to a targeted device running the affected software. When the software processes the malicious URL, the device could reload. A successful exploit could allow the attacker to cause the device to reload abnormally and deny service to legitimate users. Sustained attacks could result in an extended DoS condition.
To exploit this vulnerability, an attacker may need access to trusted, internal networks to send crafted requests to the affected software. In addition, a Cisco FWSM is affected by this vulnerability if the auth-proxy feature is
enabled. This feature is not enabled by default. These requirements could limit the likelihood of a successful exploit.
Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
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 affected systems.
Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via e-mail at email@example.com
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Cisco Multivendor Vulnerability Alerts respond to vulnerabilities identified in third-party vendors' products. These alerts contain information compiled from diverse sources and provide comprehensive technical descriptions, objective analytical assessments, workarounds and practical safeguards, and links to vendor advisories and patches.