CVE-2007-2455 in Parallels
Summary
by MITRE
Parallels allows local users to cause a denial of service (virtual machine abort) via (1) certain INT instructions, as demonstrated by INT 0xAA; (2) an IRET instruction when an invalid address is at the top of the stack; (3) a malformed MOVNTI instruction, as demonstrated by using a register as a destination; or a write operation to (4) SEGR6 or (5) SEGR7.
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Analysis
by VulDB Data Team • 10/17/2017
The vulnerability described in CVE-2007-2455 represents a critical security flaw in Parallels virtualization software that enables local users to trigger denial of service conditions within virtual machines. This vulnerability exists within the virtualization layer's instruction handling mechanisms and demonstrates how improper validation of processor instructions can lead to system instability and complete virtual machine termination. The flaw affects the hypervisor's ability to properly process certain x86 processor instructions, creating exploitable conditions that can be leveraged by malicious local users to disrupt virtualized environments.
The technical implementation of this vulnerability involves several distinct instruction-based attack vectors that exploit different aspects of virtual machine execution. The first vector utilizes specific INT instructions, particularly INT 0xAA, which are typically reserved for system calls and can cause unexpected behavior when improperly handled by the virtualization layer. The second vector involves IRET instructions that become problematic when the stack contains invalid addresses, creating a scenario where the virtual machine attempts to return from an interrupt with corrupted stack state. The third vector targets MOVNTI instructions, which are normally used for non-temporal data movement operations, but become exploitable when registers are used as destinations rather than memory addresses. Additionally, write operations to SEGR6 and SEGR7 registers demonstrate that the vulnerability extends beyond instruction execution to include register manipulation attacks.
From an operational impact perspective, this vulnerability represents a significant threat to virtualized environments as it allows local users to cause complete virtual machine aborts without requiring elevated privileges. The attack vectors are particularly concerning because they leverage standard processor instructions that are commonly used in legitimate system operations, making detection and prevention challenging. When exploited, these conditions result in immediate virtual machine termination, effectively creating a denial of service condition that can disrupt critical applications running within the virtualized environment. The vulnerability is especially dangerous in multi-tenant virtualization environments where one user's malicious actions can potentially affect other virtual machines running on the same host system.
The vulnerability aligns with several CWE classifications including CWE-119 for memory safety issues, CWE-248 for improper exception handling, and CWE-362 for race conditions that could be exploited in virtualization contexts. From an ATT&CK framework perspective, this vulnerability maps to T1499 for endpoint denial of service and T1059 for command and scripting interpreter usage. The attack surface is particularly relevant for defense in depth strategies as it demonstrates how hypervisor-level vulnerabilities can be exploited through seemingly benign processor instruction sequences. Organizations using Parallels virtualization software should consider implementing additional monitoring and validation mechanisms to detect potential exploitation attempts, while also ensuring that virtual machine environments are properly isolated to prevent cross-tenant impact.
Mitigation strategies should focus on updating to patched versions of Parallels software where available, implementing strict instruction validation within virtual machine configurations, and establishing monitoring protocols to detect unusual instruction sequences that might indicate exploitation attempts. Network segmentation and proper access controls should be implemented to limit local user privileges within virtualized environments, while also maintaining comprehensive logging of virtual machine activities for forensic analysis. The vulnerability underscores the importance of virtualization security and highlights how low-level processor instruction handling can create significant security risks when not properly validated in virtualized environments. Organizations should also consider implementing additional security measures such as hypervisor hardening, regular vulnerability assessments, and proper incident response procedures to address potential exploitation of similar virtualization-level vulnerabilities.