CVE-2015-0712 in StarOS
Summary
by MITRE
The session-manager service in Cisco StarOS 12.0, 12.2(300), 14.0, and 14.0(600) on ASR 5000 devices allows remote attackers to cause a denial of service (service reload and packet loss) via malformed HTTP packets, aka Bug ID CSCud14217.
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Analysis
by VulDB Data Team • 03/22/2019
The vulnerability described in CVE-2015-0712 represents a critical denial of service weakness within the session-manager service of Cisco StarOS software versions 12.0, 12.2(300), 14.0, and 14.0(600) running on ASR 5000 devices. This flaw specifically targets the handling of malformed HTTP packets, which can be exploited by remote attackers to disrupt service availability. The vulnerability falls under the category of input validation failures and can be classified as a CWE-20 weakness, representing improper input validation that leads to system instability. The affected Cisco ASR 5000 series devices are widely deployed in carrier-grade environments where continuous service availability is paramount, making this vulnerability particularly concerning for network operators and service providers who rely on these platforms for critical infrastructure operations.
The technical exploitation of this vulnerability occurs when the session-manager service processes malformed HTTP packets that do not conform to standard protocol specifications. These malformed packets trigger an unexpected behavior in the service's packet handling mechanisms, causing the system to reload or experience significant packet loss. The attack vector is entirely remote, meaning that an attacker does not require physical access or local network privileges to exploit the vulnerability. The service reload functionality essentially forces the device to restart its session management processes, leading to temporary service interruption and potential data loss. This behavior aligns with ATT&CK technique T1499.004, which involves network disruption attacks that cause denial of service conditions. The specific mechanism involves the service failing to properly validate incoming HTTP headers or request structures, allowing maliciously crafted packets to trigger an internal error condition that results in system instability.
The operational impact of this vulnerability extends beyond simple service disruption to potentially affect large-scale network operations that depend on ASR 5000 devices. When the session-manager service reloads due to malformed HTTP packet processing, network traffic experiences interruptions that can cascade across interconnected systems. The packet loss component of the vulnerability can lead to incomplete data transmission and application-level failures, particularly affecting web-based services and HTTP traffic that flows through these devices. For telecommunications carriers and enterprise networks using these platforms, such disruptions can result in significant revenue loss and customer dissatisfaction. The vulnerability affects the fundamental session management capabilities of the system, which are essential for maintaining user connections and service continuity. The fact that this vulnerability affects multiple software versions indicates a persistent flaw in the codebase that was not adequately addressed through previous patches or updates, highlighting potential gaps in the software development lifecycle and security testing processes.
Mitigation strategies for this vulnerability should include immediate implementation of network access controls to restrict HTTP traffic to only trusted sources, thereby reducing the attack surface. Cisco released specific software updates and patches that address this vulnerability, which should be applied as soon as possible to prevent exploitation. Network administrators should also implement monitoring and alerting mechanisms to detect unusual patterns of service reloads or packet loss that may indicate exploitation attempts. The recommended approach involves configuring the device to properly validate HTTP packet structures and implement rate limiting for incoming HTTP requests to prevent abuse of the vulnerability. Additionally, network segmentation strategies should be employed to isolate critical services from potential attack vectors. Organizations should also consider implementing intrusion detection systems that can identify and block malformed HTTP packets before they reach the vulnerable session-manager service. The vulnerability demonstrates the importance of maintaining current software versions and implementing robust security practices that include regular vulnerability assessments and penetration testing to identify similar weaknesses in network infrastructure components.