CVE-2021-22548 in Asylo
Summary
by MITRE • 06/08/2021
An attacker can change the pointer to untrusted memory to point to trusted memory region which causes copying trusted memory to trusted memory, if the latter is later copied out, it allows for reading of memory regions from the trusted region. It is recommended to update past 0.6.2 or git commit https://github.com/google/asylo/commit/53ed5d8fd8118ced1466e509606dd2f473707a5c
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Analysis
by VulDB Data Team • 06/11/2021
This vulnerability resides within the asylo framework, a trusted execution environment library developed by google, and represents a critical memory management flaw that undermines the security boundaries intended to protect sensitive data. The issue manifests when an attacker manipulates a pointer that should reference untrusted memory to instead point to a trusted memory region. This manipulation occurs through a specific flaw in the framework's memory handling mechanisms, creating a scenario where data copying operations behave unexpectedly and compromise the isolation guarantees that trusted execution environments are designed to provide. The vulnerability is particularly dangerous because it operates at the memory management level, directly affecting how the system handles data movement between different memory spaces.
The technical implementation of this flaw involves a pointer manipulation attack that exploits the framework's trust assumptions about memory regions. When the system processes memory operations, it incorrectly handles the pointer dereferencing logic, allowing an attacker to redirect memory access patterns from untrusted to trusted regions. This creates a condition where trusted memory contents are copied to trusted memory locations, but the subsequent copying operations to external destinations can expose sensitive data from the trusted regions. The vulnerability specifically affects versions prior to 0.6.2 of the asylo framework, indicating a regression or design flaw that was introduced in the codebase and subsequently addressed through a specific commit. The root cause can be categorized under CWE-121, which deals with stack-based buffer overflow conditions, though the manifestation here involves memory pointer manipulation rather than traditional buffer overflows.
The operational impact of this vulnerability extends beyond simple information disclosure, as it fundamentally compromises the security model of the trusted execution environment. An attacker who successfully exploits this vulnerability can gain access to sensitive data that should remain protected within trusted memory regions, potentially exposing cryptographic keys, private data, or other confidential information. The attack vector requires careful manipulation of memory pointers but does not necessarily require elevated privileges, making it particularly concerning for systems where the asylo framework is used to protect sensitive operations. This vulnerability affects systems that rely on asylo for secure enclave operations, potentially undermining the entire security posture of applications that depend on trusted execution environments for data protection.
The recommended mitigation strategy involves updating to version 0.6.2 or applying the specific fix from commit 53ed5d8fd8118ced1466e509606dd2f473707a5c in the asylo github repository. This update addresses the pointer handling logic that enables the memory manipulation attack and restores proper isolation between trusted and untrusted memory regions. Organizations should prioritize this update across all systems that utilize the asylo framework, particularly those handling sensitive data in trusted execution environments. Additionally, system administrators should monitor for any potential exploitation attempts and implement additional security monitoring to detect anomalous memory access patterns that might indicate exploitation of this vulnerability. The fix aligns with security best practices for maintaining memory safety and preventing information disclosure in trusted computing environments, as outlined in various security frameworks including those addressing memory safety vulnerabilities under the attack techniques described in the mitre attack framework.