CVE-2017-6607 in ASA
Summary
by MITRE
A vulnerability in the DNS code of Cisco ASA Software could allow an unauthenticated, remote attacker to cause an affected device to reload or corrupt the information present in the device's local DNS cache. The vulnerability is due to a flaw in handling crafted DNS response messages. An attacker could exploit this vulnerability by triggering a DNS request from the Cisco ASA Software and replying with a crafted response. A successful exploit could cause the device to reload, resulting in a denial of service (DoS) condition or corruption of the local DNS cache information. Note: Only traffic directed to the affected device can be used to exploit this vulnerability. This vulnerability affects Cisco ASA Software configured in routed or transparent firewall mode and single or multiple context mode. This vulnerability can be triggered by IPv4 and IPv6 traffic. 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: 9.1(7.12) 9.2(4.18) 9.4(3.12) 9.5(3.2) 9.6(2.2). Cisco Bug IDs: CSCvb40898.
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Analysis
by VulDB Data Team • 08/25/2024
The vulnerability identified as CVE-2017-6607 represents a critical flaw in Cisco Adaptive Security Appliance (ASA) software that enables remote attackers to disrupt network operations through manipulated DNS responses. This weakness resides within the DNS processing mechanisms of the affected security appliances, specifically manifesting when the system receives and processes crafted DNS reply messages. The vulnerability stems from inadequate validation of incoming DNS responses, creating an avenue for malicious actors to exploit the device's DNS handling capabilities without requiring authentication credentials. The flaw impacts devices operating in both routed and transparent firewall modes, as well as those configured in single or multiple context environments, demonstrating the widespread nature of the potential compromise. According to industry standards such as CWE-129, this vulnerability aligns with improper input validation issues that can lead to denial of service conditions and data corruption scenarios.
The operational impact of CVE-2017-6607 extends beyond simple service disruption to potentially compromise the integrity of critical network infrastructure. When successfully exploited, the vulnerability can force affected Cisco ASA devices to undergo unexpected reloads, creating temporary network outages that disrupt business operations and communications. Additionally, the corruption of local DNS cache information can lead to persistent connectivity issues, where legitimate network traffic may be misrouted or blocked due to poisoned cache entries. This dual nature of the vulnerability - causing both immediate denial of service through device reloads and longer-term cache corruption - amplifies its potential damage to network availability and reliability. The attack vector requires only that malicious traffic be directed toward the vulnerable device, making it particularly concerning for publicly accessible network infrastructure where such traffic can be easily generated and transmitted.
Cisco's official patching strategy addressed this vulnerability across multiple software versions, with fixed releases including 9.1(7.12), 9.2(4.18), 9.4(3.12), 9.5(3.2), and 9.6(2.2). The vulnerability affects a broad range of Cisco ASA products including the ASA 1000V Cloud Firewall, 5500 Series appliances, 5500-X Next-Generation Firewalls, services modules for Catalyst switches, ASAv virtual appliances, Firepower 9300 ASA Security Modules, and ISA 3000 Industrial Security Appliances. The exploitation can occur through both IPv4 and IPv6 traffic, indicating that network administrators must consider both protocol versions when implementing mitigation strategies. This vulnerability maps to ATT&CK technique T1499.004, which covers network denial of service attacks, and demonstrates how DNS-related vulnerabilities can be leveraged for broader operational disruption. The affected devices operate in various deployment scenarios, from cloud-based virtual appliances to industrial security appliances, highlighting the need for comprehensive vulnerability management across diverse network environments.
Organizations should implement immediate mitigation measures including applying the recommended software patches, configuring access control lists to restrict DNS traffic from untrusted sources, and monitoring network traffic for suspicious DNS response patterns. Network segmentation strategies can help limit the potential impact of exploitation by isolating vulnerable devices from critical network segments. Security teams should also consider implementing DNS cache monitoring and alerting mechanisms to detect early signs of cache corruption or unauthorized reload attempts. The vulnerability's classification under CWE-129 and its mapping to ATT&CK techniques emphasize the importance of robust input validation controls and network monitoring capabilities. Additionally, organizations should conduct thorough vulnerability assessments to identify all instances of affected Cisco ASA software across their network infrastructure and prioritize remediation efforts based on risk exposure and business criticality.