CVE-2016-6398 in IOS
Summary
by MITRE
The PPTP server in Cisco IOS 15.5(3)M does not properly initialize packet buffers, which allows remote attackers to obtain sensitive information from earlier network communication by reading packet data, aka Bug ID CSCvb16274.
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Analysis
by VulDB Data Team • 09/14/2022
The vulnerability identified as CVE-2016-6398 represents a critical information disclosure flaw within Cisco IOS 15.5(3)M PPTP server implementations. This weakness stems from improper initialization of packet buffers during the processing of network communications, creating a scenario where attackers can potentially access sensitive data from previous network exchanges. The vulnerability specifically affects Cisco IOS versions that incorporate PPTP server functionality, making it particularly concerning for organizations relying on these networking devices for remote access services.
The technical root cause of this vulnerability lies in the insufficient memory initialization practices within the PPTP server module. When processing incoming packets, the system fails to properly clear or initialize buffer memory areas before reuse, leading to potential information leakage. This behavior creates a condition where residual data from previous network communications remains accessible within memory buffers, allowing unauthorized parties to extract confidential information through carefully crafted network requests. The flaw operates at the protocol processing layer, specifically impacting how the PPTP server handles packet data structures and memory management during network communication processing.
From an operational impact perspective, this vulnerability poses significant risks to organizations utilizing Cisco IOS devices with PPTP server capabilities. Attackers can exploit this weakness to recover sensitive information such as authentication credentials, session data, or other confidential network communications that may have occurred previously. The remote nature of the attack means that adversaries do not require physical access to the device or local network privileges to exploit the vulnerability. This information disclosure can lead to further compromise of network security, potential credential theft, and unauthorized access to protected resources within the network infrastructure.
Security professionals should consider this vulnerability in the context of broader attack frameworks, particularly those related to information gathering and reconnaissance activities. The flaw aligns with CWE-1186, which addresses improper initialization of resources, and can be mapped to ATT&CK techniques involving credential access and information discovery. Organizations should implement immediate mitigations including applying Cisco's security patches and updates, disabling PPTP server functionality where possible, and monitoring network traffic for potential exploitation attempts. Additionally, network segmentation and access controls should be strengthened to limit potential attack vectors and reduce the overall risk surface associated with vulnerable Cisco IOS implementations.