CVE-2007-2893 in Bochs
Summary
by MITRE
Heap-based buffer overflow in the bx_ne2k_c::rx_frame function in iodev/ne2k.cc in the emulated NE2000 device in Bochs 2.3 allows local users of the guest operating system to write to arbitrary memory locations and gain privileges on the host operating system via vectors that cause TXCNT register values to exceed the device memory size, aka "RX Frame heap overflow."
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Analysis
by VulDB Data Team • 07/20/2021
The vulnerability identified as CVE-2007-2893 represents a critical heap-based buffer overflow within the Bochs 2.3 virtualization environment, specifically affecting the emulated NE2000 network device. This flaw exists in the bx_ne2k_c::rx_frame function located in iodev/ne2k.cc, where improper bounds checking allows attackers to manipulate memory allocation patterns during network packet processing. The vulnerability arises from the device's inability to properly validate TXCNT register values against available device memory boundaries, creating a condition where malicious input can cause unauthorized memory writes. The flaw demonstrates a classic heap overflow pattern that can be exploited to execute arbitrary code with the privileges of the host operating system, making it particularly dangerous in virtualized environments where guest and host systems share resources.
The technical exploitation of this vulnerability occurs when a local user within the guest operating system manipulates network traffic to cause the TXCNT register values to exceed the allocated device memory size. This condition triggers a heap-based buffer overflow in the rx_frame function, where the device attempts to write data beyond the allocated memory boundaries. The flaw is categorized under CWE-121 as a heap-based buffer overflow, specifically manifesting as an improper restriction of operations within a memory buffer. The attack vector requires local access to the guest system but can result in privilege escalation to the host level, making it a significant concern for virtualization security. The vulnerability stems from inadequate input validation and memory management within the emulated network device implementation, where the system fails to properly enforce memory limits during frame reception operations.
The operational impact of CVE-2007-2893 extends beyond simple privilege escalation, as it fundamentally undermines the security isolation that virtualization environments are designed to provide. When successfully exploited, the vulnerability allows attackers to execute code on the host system with elevated privileges, potentially leading to complete system compromise, data theft, or further lateral movement within the network infrastructure. The attack requires local access to the guest operating system but does not need network-level privileges, making it particularly dangerous in multi-tenant virtualized environments where guest users may have limited access but could leverage this vulnerability to escape their virtual boundaries. This type of vulnerability is classified under the ATT&CK technique T1055 for Process Injection and T1074 for Data Staged, as it enables attackers to manipulate memory and execute code on the host system through the virtualization layer.
Mitigation strategies for this vulnerability primarily focus on updating to patched versions of Bochs where the memory management in the emulated NE2000 device has been corrected to properly validate register values against memory boundaries. Administrators should implement network segmentation and access controls to limit local user privileges within guest systems, as well as monitor for unusual network traffic patterns that might indicate exploitation attempts. The fix typically involves adding proper bounds checking in the rx_frame function to ensure that TXCNT register values do not exceed available device memory, preventing the heap overflow condition. Additionally, virtualization administrators should consider implementing memory protection mechanisms such as DEP (Data Execution Prevention) and ASLR (Address Space Layout Randomization) to make exploitation more difficult even if the underlying vulnerability persists. Organizations should also conduct regular vulnerability assessments of their virtualization infrastructure and maintain up-to-date security patches to prevent similar issues in other emulated hardware components.