CVE-2010-2818 in Firewall Services Module Software
Summary
by MITRE
Unspecified vulnerability in the SunRPC inspection feature on the Cisco Firewall Services Module (FWSM) with software 3.1 before 3.1(17.2), 3.2 before 3.2(16.1), 4.0 before 4.0(10.1), and 4.1 before 4.1(1.1) for Catalyst 6500 series switches and 7600 series routers allows remote attackers to cause a denial of service (device reload) via crafted SunRPC messages, aka Bug ID CSCte61710.
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Analysis
by VulDB Data Team • 09/22/2021
The vulnerability described in CVE-2010-2818 represents a critical flaw in the SunRPC inspection capabilities of Cisco Firewall Services Module implementations. This issue affects multiple versions of the FWSM software running on Catalyst 6500 series switches and 7600 series routers, specifically targeting software versions 3.1 before 3.1(17.2), 3.2 before 3.2(16.1), 4.0 before 4.0(10.1), and 4.1 before 4.1(1.1). The vulnerability manifests through crafted SunRPC messages that can be transmitted over the network to exploit a weakness in how the device processes these specific protocol communications.
The technical nature of this flaw resides in the insufficient validation and handling of SunRPC inspection features within the Cisco FWSM architecture. SunRPC represents a remote procedure call protocol that enables programs to execute code in other address spaces transparently. When the FWSM processes these messages, it fails to properly validate the incoming data structure, leading to a condition where malformed or specially crafted SunRPC packets can trigger unexpected behavior within the device's processing engine. This vulnerability is classified under CWE-129 as an insufficient input validation issue, where the system fails to properly validate the boundaries and structure of input data before processing.
The operational impact of this vulnerability is severe and directly translates to a denial of service condition that can cause complete device reloads. Attackers exploiting this weakness can remotely initiate a device restart sequence that effectively disrupts network services, creating temporary network outages that can span from minutes to hours depending on the recovery time of the affected system. The attack vector requires no authentication and can be executed from remote locations, making it particularly dangerous for network infrastructure devices that are often exposed to untrusted network traffic. This vulnerability directly maps to the ATT&CK technique T1499.004 for network disruption and can be classified under the broader category of denial of service attacks that compromise availability.
The exploitation of this vulnerability demonstrates how protocol inspection features can become attack vectors when input validation is inadequate. The FWSM's SunRPC inspection functionality is designed to monitor and control RPC communications passing through the firewall, but the implementation contains a flaw that allows attackers to bypass normal protocol validation and trigger internal system errors. This represents a classic case of insufficient error handling where malformed protocol data causes the system to crash or restart rather than gracefully rejecting the invalid input. Organizations implementing Cisco FWSM solutions should consider this vulnerability as a high-priority threat that can be exploited for network disruption attacks without requiring privileged access or complex attack infrastructure.
Mitigation strategies for this vulnerability primarily focus on applying the appropriate software patches released by Cisco to address the specific SunRPC inspection flaw. The affected versions should be upgraded to software releases that contain the necessary fixes for CVE-2010-2818, with particular attention to the patch levels mentioned in the advisory. Network administrators should also consider implementing additional network segmentation and access control measures to limit exposure of vulnerable FWSM devices to untrusted traffic. While waiting for patches, temporary workarounds such as disabling SunRPC inspection functionality or implementing stricter access control lists may provide reduced risk, though these measures should not be considered permanent solutions. The vulnerability serves as a reminder of the importance of maintaining current software versions and the critical nature of protocol validation in network security devices.