DoLTEst: In-depth Downlink Negative Testing Framework for LTE Devices

An implementation flaw in LTE control plane protocols at end-user devices directly leads to severe security threats. In order to uncover these flaws, conducting negative testing is a promising approach, whose test case only contains invalid or prohibited messages. Despite its importance, the cellular standard mostly focuses on positive test cases, producing many implementation vulnerabilities unchecked, as evidenced by many existing vulnerabilities. To fill this gap, we present DOLTEST, a negative testing framework, which can comprehensively test an end-user device. Enumerable test cases with a deterministic oracle produced from detailed specification analysis make it suitable to be used as a standard to find implementation vulnerabilities. We uncovered 26 implementation flaws from 43 devices from 5 different baseband manufacturers by using DOLTEST, demonstrating its effectiveness.