BaseFortify

Executive Summary

This is a heap out-of-bounds write vulnerability in Oracle VM VirtualBox's PCNet (Am79C970A) network device model. The issue occurs in the pcnetReceiveNoSync function where the receive write cursor is incorrectly set to pThis->abRecvBuf[8], leaving only 4088 usable bytes in a 4096-byte buffer. A guest with access to the emulated PCNet NIC can exploit this by using internal loopback mode with a chained transmit descriptor ring to send a 4096-byte frame into the receive path without proper bounds checking.

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Detection Guidance

Detecting this vulnerability requires checking the VirtualBox version and inspecting network device configurations. Use commands like 'VBoxManage --version' to verify the installed version. If running versions 7.0.x through 7.0.26, the system is vulnerable. Additionally, monitor for unusual network activity or crashes in the VirtualBox host process.

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Impact Analysis

A malicious or compromised guest could corrupt host-side device state in the VirtualBox host process. This results in a guest-to-host memory-safety violation that could impact system integrity and availability. In severe cases, it could serve as a step toward gaining control of the host system.

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Compliance Impact

This vulnerability could potentially impact compliance with GDPR and HIPAA by allowing a guest OS to corrupt host memory, leading to unauthorized data access or modification. Such memory-safety violations may result in data breaches or loss of integrity, which are critical concerns under these regulations.

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Mitigation Strategies

Upgrade VirtualBox to version 7.2.8 or later immediately. If upgrading is not possible, disable the PCNet (Am79C970A) network device in guest VMs and switch to a different network adapter type like Intel PRO/1000. Avoid using internal loopback mode (CSR15 LOOP) in vulnerable configurations.

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