CVE-2011-4022 in Intrusion Prevention System
Summary
by MITRE
The sensor in Cisco Intrusion Prevention System (IPS) 7.0 and 7.1 allows remote attackers to cause a denial of service (file-handle exhaustion and mainApp hang) by making authentication attempts that exceed the configured limit, aka Bug ID CSCto51204.
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Analysis
by VulDB Data Team • 01/28/2018
The vulnerability identified as CVE-2011-4022 affects Cisco Intrusion Prevention System versions 7.0 and 7.1, specifically targeting the sensor component that handles authentication processes. This flaw represents a significant security concern as it enables remote attackers to execute a denial of service attack against the affected system. The vulnerability stems from insufficient handling of authentication attempts that exceed the configured limit, creating a condition where legitimate system operations become compromised. The issue manifests through a file-handle exhaustion scenario that ultimately leads to the main application hanging, effectively rendering the intrusion prevention system non-functional and unable to perform its core security monitoring duties.
The technical implementation of this vulnerability resides in the authentication subsystem of the Cisco IPS sensor, where the system fails to properly manage and terminate authentication sessions when the maximum allowed attempts are exceeded. This flaw operates under the principle of resource exhaustion, where each failed authentication attempt consumes system file handles and memory resources without proper cleanup mechanisms. The vulnerability specifically targets the main application process that manages the sensor operations, causing it to become unresponsive and effectively disabling the system's ability to detect and prevent intrusion attempts. The attack vector is remote, meaning that adversaries can exploit this weakness without requiring physical access to the system, making it particularly dangerous in networked environments where the IPS sensor is exposed to external threats.
From an operational impact perspective, this vulnerability creates a critical service disruption scenario where the affected Cisco IPS sensor becomes completely non-responsive, leaving the network segment it protects vulnerable to various cyber threats. The file-handle exhaustion condition prevents the system from establishing new connections or processing legitimate authentication requests, while the mainApp hang completely disables the sensor's ability to monitor network traffic and detect malicious activities. This situation directly violates the fundamental security principle of availability, as the system becomes unusable for its intended purpose of protecting network infrastructure. The impact extends beyond simple service interruption, as organizations may experience increased risk of successful cyber attacks during the period when the sensor is non-operational, potentially leading to data breaches or other security incidents.
Organizations should implement multiple layers of mitigation strategies to address this vulnerability, beginning with immediate deployment of Cisco's official security patches and updates that resolve the authentication handling flaw. Network administrators should also consider implementing rate limiting and access control measures to reduce the effectiveness of potential exploitation attempts, while monitoring systems should be configured to detect unusual authentication patterns that might indicate an ongoing attack. The vulnerability aligns with CWE-400, which covers "Uncontrolled Resource Consumption," and demonstrates characteristics consistent with ATT&CK technique T1499.004, "Endpoint Denial of Service," where adversaries target system resources to prevent legitimate use. Additionally, this issue reflects the broader category of privilege escalation vulnerabilities that can be leveraged to gain unauthorized access to critical network security infrastructure. Organizations should also review their incident response procedures to ensure they can quickly detect and remediate such denial of service conditions, as the affected systems may require complete restart or manual intervention to restore normal operations.