CVE-2018-20742 in RISE Opaque
Summary
by MITRE
An issue was discovered in UC Berkeley RISE Opaque before 2018-12-01. There is no boundary check on ocall_malloc. The return value could be a pointer to enclave memory. It could cause an arbitrary enclave memory write.
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Analysis
by VulDB Data Team • 07/03/2023
The vulnerability identified as CVE-2018-20742 represents a critical security flaw in the UC Berkeley RISE Opaque system prior to the specified date. This issue stems from insufficient input validation mechanisms within the ocall_malloc function, which serves as a crucial interface between the untrusted user space and the trusted enclave environment. The absence of proper boundary checks creates a dangerous condition where memory allocation requests can potentially lead to unauthorized access patterns within the enclave's protected memory space. This vulnerability manifests as a lack of proper validation for the return value from the memory allocation call, allowing malicious actors to manipulate the pointer returned by ocall_malloc to point to arbitrary locations within the enclave memory region.
The technical exploitation of this vulnerability occurs through a memory corruption attack vector that directly targets the enclave's memory management system. When ocall_malloc fails to validate input parameters and enforce proper boundary constraints, it enables attackers to craft allocation requests that result in pointer values pointing to sensitive enclave memory locations. This creates a scenario where an attacker can effectively bypass the normal memory isolation mechanisms that protect enclave data from external access. The vulnerability's classification aligns with CWE-129, which addresses insufficient input validation, and more specifically with CWE-787, concerning out-of-bounds write operations. The flaw fundamentally undermines the security model of the enclave by allowing memory write operations that should be restricted to the enclave's own memory management subsystem to be manipulated from external contexts.
The operational impact of this vulnerability extends beyond simple memory corruption, creating a potential pathway for complete enclave compromise. An attacker who successfully exploits this issue can achieve arbitrary memory writes within the enclave, effectively allowing them to modify critical data structures, overwrite function pointers, or corrupt the enclave's execution environment. This capability directly violates the fundamental security principles that enclaves are designed to maintain, as it enables unauthorized modification of protected memory contents. The vulnerability's severity is amplified by its potential to be leveraged as a stepping stone for more sophisticated attacks, including privilege escalation, data exfiltration, or complete system compromise. From an attacker's perspective, this flaw represents a critical entry point that can be exploited to undermine the entire security architecture built around the enclave system.
Mitigation strategies for this vulnerability must address the core issue of insufficient input validation within the ocall_malloc function. The primary solution involves implementing comprehensive boundary checks and input validation mechanisms that ensure all memory allocation requests are properly validated before any memory operations are performed. Security patches should enforce strict validation of allocation parameters, including size limits and memory address ranges, to prevent the return of pointers that could point to arbitrary enclave memory locations. Additionally, the system should implement proper memory isolation checks that verify the legitimacy of memory addresses returned by the allocation function. Organizations should also consider implementing runtime monitoring and anomaly detection systems that can identify suspicious memory access patterns that might indicate exploitation attempts. This vulnerability highlights the critical importance of maintaining strict security boundaries between trusted and untrusted execution environments, and serves as a reminder of the necessity for comprehensive input validation in all system interfaces that interact with sensitive memory spaces. The remediation approach should align with security best practices outlined in the ATT&CK framework under the T1068 technique for exploit for privilege escalation, emphasizing the need for robust memory management controls in secure computing environments.