CVE-2018-6480 in CCN-lite
Summary
by MITRE
A type confusion issue was discovered in CCN-lite 2, leading to a memory access violation and a failure of the nonce feature (which, for example, helped with loop prevention). ccnl_fwd_handleInterest assumes that the union member s is of type ccnl_pktdetail_ndntlv_s. However, if the type is in fact struct ccnl_pktdetail_ccntlv_s or struct ccnl_pktdetail_iottlv_s, the memory at that point is either uninitialised or points to data that is not a nonce, which renders the code using the local variable nonce pointless. A later nonce check is insufficient.
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Analysis
by VulDB Data Team • 02/03/2023
The vulnerability CVE-2018-6480 represents a critical type confusion flaw in CCN-lite 2, a content centric networking implementation that serves as a foundation for distributed content delivery systems. This issue stems from improper handling of union data structures within the ccnl_fwd_handleInterest function, where the system assumes a specific data type while potentially encountering different structures. The flaw manifests when the code processes interest packets and attempts to access nonce values for loop prevention mechanisms, fundamentally compromising the security and operational integrity of the networking protocol. The vulnerability is classified under CWE-466 as "Use of Type-Confusion Vulnerability," which directly relates to improper handling of data type assumptions in memory management operations.
The technical implementation of this vulnerability occurs through the misuse of union members within the ccnl_pktdetail structure, specifically when the code assumes that the union member s corresponds to ccnl_pktdetail_ndntlv_s type. However, when the actual packet type is either ccnl_pktdetail_ccntlv_s or ccnl_pktdetail_iottlv_s, the memory access patterns become inconsistent and unpredictable. This type confusion results in accessing uninitialized memory or data that does not conform to the expected nonce structure, causing the nonce feature to fail completely. The failure of nonce functionality directly impacts loop prevention mechanisms that are essential for maintaining network stability and preventing denial-of-service conditions. The memory access violation occurs at the point where the code attempts to read the nonce field, which is not properly aligned or initialized according to the expected data structure, creating a potential exploitation vector for remote attackers.
The operational impact of this vulnerability extends beyond simple memory access violations to compromise fundamental security features of the CCN-lite implementation. The nonce failure undermines loop prevention capabilities, which are crucial for maintaining network integrity in content centric networking environments where packet forwarding loops can cause significant network degradation. Attackers could potentially exploit this vulnerability to create persistent forwarding loops or manipulate packet routing behaviors, leading to network congestion or service disruption. The vulnerability affects the overall reliability of the CCN-lite framework and could be leveraged to bypass security controls that depend on proper nonce validation. This type of vulnerability is particularly concerning in distributed systems where content centric networking protocols are deployed for critical infrastructure applications.
Mitigation strategies for CVE-2018-6480 require comprehensive code review and implementation of proper type checking mechanisms within the union handling code. The recommended approach involves implementing explicit type validation before accessing union members, ensuring that the actual packet type matches the expected structure before processing nonce values. Security patches should enforce proper initialization of union members and implement bounds checking to prevent access to uninitialized memory regions. Organizations should consider implementing defensive programming practices such as using tagged unions or explicit type discriminators to prevent type confusion scenarios. Additionally, the implementation should include runtime checks that verify the integrity of packet structures before attempting to extract nonce values. This vulnerability highlights the importance of proper memory management practices and adherence to secure coding standards, particularly in network protocol implementations where type safety is paramount for maintaining system integrity. The remediation process should also include thorough regression testing to ensure that nonce functionality is properly restored and that no additional type confusion vulnerabilities exist within the codebase.