Caching techniques can be used to reduce bandwidth consumption and data access delay in wireless ad hoc networks. When cache is used, cache consistency issues must be addressed. To maintain strong cache consistency in some strategic scenarios (e.g., battle fields), the invalidation-based approach is preferred due to its low overhead. However, this approach may suffer from some security attacks. For example, a malicious node (intruder) may drop, insert or modify invalidation messages to mislead the receivers to use stale data or unnecessarily invalidate the data that is still valid. In this paper, we propose a solution based on the IR-based cache invalidation strategy to prevent intruders from dropping or modifying the invalidation messages. Although digital signatures can be used to protect IRs, it has significantly high overhead in terms of computation and bandwidth consumption. To address this problem, we propose afamily of randomized grouping based schemes for intrusion detection and damage recovery. Extensive analysis and simulations are used to evaluate the proposed schemes. The results show that our solution can achieve a good level of security with low overhead.