CVE-2020-10702 in QEMU
Summary
by MITRE
A flaw was found in QEMU in the implementation of the Pointer Authentication (PAuth) support for ARM introduced in version 4.0 and fixed in version 5.0.0. A general failure of the signature generation process caused every PAuth-enforced pointer to be signed with the same signature. A local attacker could obtain the signature of a protected pointer and abuse this flaw to bypass PAuth protection for all programs running on QEMU.
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Analysis
by VulDB Data Team • 10/26/2024
The vulnerability CVE-2020-10702 represents a critical flaw in QEMU's implementation of Pointer Authentication (PAuth) support for ARM architecture systems. This issue emerged in QEMU version 4.0 and remained unresolved until version 5.0.0, affecting virtualized environments where ARM-based systems are emulated. The flaw specifically targets the cryptographic signature generation mechanism that forms the foundation of PAuth protection, which is designed to prevent pointer corruption and unauthorized code execution by validating pointer integrity through cryptographic signatures. The vulnerability fundamentally undermines the security guarantees that PAuth is intended to provide within virtualized ARM environments.
The technical implementation flaw lies in the signature generation process where every PAuth-enforced pointer receives identical cryptographic signatures regardless of the actual pointer values or memory locations. This deterministic failure means that the cryptographic protection mechanism becomes completely ineffective, as the signature verification process cannot distinguish between legitimate and malicious pointers. The flaw essentially transforms PAuth from a security enhancement into a trivial vulnerability that can be easily exploited. This issue is classified as a weakness in cryptographic implementation under CWE-327, specifically involving the use of weak or broken cryptographic algorithms that fail to provide proper entropy and uniqueness in signature generation.
The operational impact of this vulnerability is severe for any system running QEMU with ARM virtualization enabled, particularly in environments where security-sensitive applications are executed. A local attacker with access to the virtualized environment can extract the predetermined signature of any protected pointer and subsequently bypass all PAuth protections across all programs running within the QEMU virtual machine. This capability allows for sophisticated attacks including arbitrary code execution, privilege escalation, and bypass of memory safety mechanisms that depend on PAuth for their effectiveness. The vulnerability affects the integrity of the entire virtualization stack, as it undermines the fundamental security assumptions of pointer authentication within ARM-based virtualized systems.
Mitigation strategies for CVE-2020-10702 require immediate upgrade to QEMU version 5.0.0 or later where the flaw has been properly addressed. Organizations should also implement additional monitoring and access controls to detect potential exploitation attempts within their virtualized environments. The fix typically involves correcting the cryptographic signature generation algorithm to ensure proper entropy and uniqueness in each signature creation process, aligning with ATT&CK technique T1059.007 for execution through virtualization and containerization. Security teams should also consider implementing memory integrity monitoring and regular vulnerability assessments of their virtualization infrastructure to prevent similar issues from arising in other components of their security architecture.