CVE-2016-6380 in IOS
Summary
by MITRE
The DNS forwarder in Cisco IOS 12.0 through 12.4 and 15.0 through 15.6 and IOS XE 3.1 through 3.15 allows remote attackers to obtain sensitive information from process memory or cause a denial of service (data corruption or device reload) via a crafted DNS response, aka Bug ID CSCup90532.
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Analysis
by VulDB Data Team • 09/21/2022
The vulnerability identified as CVE-2016-6380 represents a critical security flaw in Cisco IOS and IOS XE operating systems affecting multiple version ranges including IOS 12.0 through 12.4 and 15.0 through 15.6 along with IOS XE 3.1 through 3.15. This issue resides within the DNS forwarder functionality which serves as a critical component for network infrastructure devices handling domain name resolution requests. The vulnerability stems from improper handling of crafted DNS responses that can trigger unexpected behavior in the affected systems.
The technical exploitation of this vulnerability occurs through specially crafted DNS responses that manipulate the memory structures of the affected Cisco devices. When these malformed responses are processed by the DNS forwarder, they can cause the system to expose sensitive information from process memory or induce system instability leading to data corruption. This memory exposure represents a significant information disclosure risk as attackers can potentially extract confidential data, credentials, or system configuration details that should remain protected within the device's operational memory space. The vulnerability manifests as a result of insufficient input validation and memory management within the DNS processing code.
The operational impact of this vulnerability extends beyond simple information disclosure to include potential system disruption through denial of service conditions. When exploited successfully, the vulnerability can cause either data corruption within the device's memory structures or trigger a complete device reload, effectively creating a denial of service scenario that impacts network availability. Network administrators face significant operational challenges as these attacks can be executed remotely without requiring authentication, making the vulnerability particularly dangerous in production environments where network stability and availability are paramount. The impact is especially severe for devices serving as DNS servers or forwarders within enterprise networks where they handle critical name resolution services for multiple network segments.
Security practitioners should implement immediate mitigations including applying the relevant Cisco security advisories and patches that address the memory handling flaws in the DNS forwarder implementation. Network segmentation strategies should be employed to limit the attack surface, particularly for devices that do not require DNS forwarding capabilities. Monitoring and logging of DNS traffic should be enhanced to detect anomalous patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-125: Out-of-bounds Read and CWE-20: Improper Input Validation, representing classic memory safety issues that can lead to both information disclosure and system instability. From an ATT&CK framework perspective, this vulnerability maps to T1071.004: Application Layer Protocol: DNS and T1499.004: Network Denial of Service, demonstrating how network protocol implementations can be leveraged for both reconnaissance and disruption activities. Organizations should also consider implementing DNS sinkholing or filtering mechanisms to prevent malicious DNS responses from reaching affected systems while maintaining proper network security posture through regular vulnerability assessments and security updates.