CVE-2017-6608 in ASA
Summary
by MITRE
A vulnerability in the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) code of Cisco ASA Software could allow an unauthenticated, remote attacker to cause a reload of the affected system. The vulnerability is due to improper parsing of crafted SSL or TLS packets. An attacker could exploit this vulnerability by sending a crafted packet to the affected system. Note: Only traffic directed to the affected system can be used to exploit this vulnerability. This vulnerability affects systems configured in routed and transparent firewall mode and in single or multiple context mode. This vulnerability can be triggered by IPv4 and IPv6 traffic. A valid SSL or TLS session is needed to exploit this vulnerability. This vulnerability affects Cisco ASA Software running on the following products: Cisco ASA 1000V Cloud Firewall, Cisco ASA 5500 Series Adaptive Security Appliances, Cisco ASA 5500-X Series Next-Generation Firewalls, Cisco ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers, Cisco Adaptive Security Virtual Appliance (ASAv), Cisco Firepower 9300 ASA Security Module, Cisco ISA 3000 Industrial Security Appliance. Fixed versions: 8.4(7.31) 9.0(4.39) 9.1(7) 9.2(4.6) 9.3(3.8) 9.4(2) 9.5(2). Cisco Bug IDs: CSCuv48243.
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Analysis
by VulDB Data Team • 08/25/2024
The vulnerability identified as CVE-2017-6608 represents a critical weakness in the SSL/TLS implementation of Cisco Adaptive Security Appliance (ASA) software systems. This flaw manifests as improper parsing of specially crafted SSL or TLS packets that can trigger a complete system reload without requiring authentication from an external attacker. The vulnerability operates at the network protocol level, specifically targeting the cryptographic communication handling mechanisms that are fundamental to secure network operations. The attack vector requires only that malicious packets be directed toward the affected system, making it particularly dangerous in environments where network traffic is not strictly controlled or monitored.
The technical nature of this vulnerability stems from inadequate input validation within the SSL/TLS processing code of Cisco ASA devices. When the system receives malformed SSL or TLS packets, the parsing routine fails to properly handle the unexpected data structures, leading to memory corruption or resource exhaustion that ultimately results in system instability. This behavior aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which covers buffer overflow vulnerabilities in heap memory. The vulnerability's exploitation requires a valid SSL or TLS session to be established, indicating that the attack must occur during an active cryptographic communication process rather than as a pre-authentication attack vector.
The operational impact of this vulnerability extends across multiple Cisco ASA product lines including the ASA 1000V Cloud Firewall, 5500 Series appliances, 5500-X Next-Generation Firewalls, and various other security modules. Systems configured in both routed and transparent firewall modes, as well as those operating in single or multiple context modes, are all susceptible to this attack. The vulnerability affects both IPv4 and IPv6 traffic, demonstrating the comprehensive nature of the flaw across different network protocol implementations. The attack can cause complete service disruption through system reloads, potentially leading to denial of service conditions that could compromise network security infrastructure. Organizations relying on these security appliances face significant operational risks as the vulnerability can be exploited to disrupt critical network security functions without requiring advanced attacker privileges or credentials.
Mitigation strategies for this vulnerability should focus on immediate software updates to the patched versions specified by Cisco, including releases 8.4(7.31), 9.0(4.39), 9.1(7), 9.2(4.6), 9.3(3.8), 9.4(2), and 9.5(2). Network administrators should also implement additional protective measures such as monitoring for unusual traffic patterns that might indicate exploitation attempts, configuring access control lists to restrict SSL/TLS traffic to only necessary sources, and establishing robust incident response procedures for detecting system reload events. The vulnerability's classification under the ATT&CK framework would align with T1499.004 for Network Denial of Service and T1566.001 for Spearphishing Attachment, as attackers could potentially use this vulnerability to establish persistent access through service disruption. Organizations should also consider implementing network segmentation to limit the potential impact of successful exploitation and maintain comprehensive logging of SSL/TLS session activities for forensic analysis purposes.