CVE-2013-4148 in QEMU
Summary
by MITRE
Integer signedness error in the virtio_net_load function in hw/net/virtio-net.c in QEMU 1.x before 1.7.2 allows remote attackers to execute arbitrary code via a crafted savevm image, which triggers a buffer overflow.
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Analysis
by VulDB Data Team • 06/20/2021
The vulnerability identified as CVE-2013-4148 represents a critical integer signedness error within the QEMU virtualization platform that specifically affects versions 1.x prior to 1.7.2. This flaw exists in the virtio_net_load function located in the hw/net/virtio-net.c file, which is responsible for handling virtual network device state restoration during savevm operations. The vulnerability stems from improper handling of signed integer values when processing network packet data, creating a condition where an attacker can manipulate the size parameters of network data structures to cause buffer overflows.
The technical nature of this vulnerability aligns with CWE-190, which describes integer overflow and underflow conditions, and more specifically with CWE-121, which addresses buffer overflow conditions. The flaw occurs during the restoration of virtual machine states where the virtio_net_load function fails to properly validate the signedness of integer values used to determine buffer allocation sizes. When a maliciously crafted savevm image is loaded, the function interprets certain integer values as unsigned while treating them as signed, leading to incorrect buffer size calculations that result in memory corruption. This type of error is particularly dangerous because it allows attackers to manipulate the memory layout and potentially execute arbitrary code with the privileges of the QEMU process.
The operational impact of this vulnerability extends beyond simple code execution, as it enables remote attackers to gain unauthorized access to virtualized environments. Since QEMU is widely used for virtual machine management across various platforms including cloud services and enterprise environments, exploitation of this vulnerability could compromise entire virtualized infrastructures. The attack vector requires the attacker to have access to a savevm image, which typically means they need to be able to influence the state files of virtual machines or have access to virtual machine snapshots. This vulnerability particularly affects cloud computing environments where multiple tenants share the same hypervisor, as a malicious tenant could potentially exploit this flaw to escape virtual machine isolation and compromise other guests on the same host.
Mitigation strategies for CVE-2013-4148 primarily involve upgrading QEMU to version 1.7.2 or later, which includes patches that properly handle integer signedness in the virtio_net_load function. Organizations should also implement strict access controls over virtual machine state files and ensure that only trusted entities can create or modify savevm images. Network segmentation and monitoring of virtual machine state operations can help detect potential exploitation attempts. From an ATT&CK perspective, this vulnerability maps to T1059.007 for execution through virtualization software and T1566 for initial access through malicious files. Additional defensive measures include implementing memory protection mechanisms such as stack canaries and address space layout randomization, though these provide only partial protection against this specific class of buffer overflow vulnerabilities.