CVE-2015-8743 in QEMU
Summary
by MITRE
QEMU (aka Quick Emulator) built with the NE2000 device emulation support is vulnerable to an OOB r/w access issue. It could occur while performing 'ioport' r/w operations. A privileged (CAP_SYS_RAWIO) user/process could use this flaw to leak or corrupt QEMU memory bytes.
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Analysis
by VulDB Data Team • 10/12/2022
The vulnerability identified as CVE-2015-8743 affects QEMU, a widely used open-source emulator that virtualizes hardware components for software testing and development environments. This issue specifically impacts QEMU configurations that include NE2000 network device emulation capabilities, which are commonly utilized in virtual machine deployments across various operating systems and cloud infrastructures. The vulnerability stems from inadequate bounds checking during input/output port operations, creating a critical security flaw that can be exploited by malicious actors with elevated privileges.
The technical flaw manifests as an out-of-bounds read and write condition within the NE2000 network device emulation code. When QEMU processes ioport read and write operations, the emulator fails to properly validate the memory addresses being accessed, allowing a malicious user with CAP_SYS_RAWIO capabilities to perform unauthorized memory operations. This privilege allows direct hardware access and bypasses normal kernel security mechanisms. The vulnerability specifically affects the network card emulation layer where buffer boundaries are not properly enforced during packet processing and register access operations, creating opportunities for memory corruption and information disclosure.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can lead to complete system compromise when combined with other exploitation techniques. A privileged attacker can leverage this flaw to read sensitive memory regions containing guest operating system data, hypervisor internals, or cryptographic keys stored in memory. The memory corruption aspect enables potential denial of service conditions or even arbitrary code execution within the QEMU process context. This vulnerability affects virtualized environments where QEMU serves as the underlying hypervisor component, including cloud computing platforms, development testing environments, and enterprise virtualization solutions that rely on QEMU for infrastructure virtualization.
Mitigation strategies for CVE-2015-8743 should prioritize immediate patching of QEMU installations to the latest stable versions that include proper bounds checking and memory validation routines. System administrators should also implement strict privilege controls to limit CAP_SYS_RAWIO capabilities to only essential processes and users. Network segmentation and monitoring solutions should be deployed to detect anomalous ioport access patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-129, which addresses improper validation of array index bounds, and maps to ATT&CK technique T1068, which involves exploiting privileges through system configuration vulnerabilities. Organizations should conduct comprehensive vulnerability assessments of their virtualized environments to ensure all QEMU instances are properly updated and monitored for potential exploitation attempts.