A vulnerability was found in Linux Kernel up to 4.17.2 (Operating System). It has been rated as critical. Affected by this issue is the function vbg_misc_device_ioctl of the file drivers/virt/vboxguest/vboxguest_linux.c. The manipulation as part of a Variable leads to a race condition vulnerability. Using CWE to declare the problem leads to CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. Impacted is confidentiality, and availability. CVE summarizes:

An issue was discovered in the Linux kernel through 4.17.2. vbg_misc_device_ioctl() in drivers/virt/vboxguest/vboxguest_linux.c reads the same user data twice with copy_from_user. The header part of the user data is double-fetched, and a malicious user thread can tamper with the critical variables (hdr.size_in and hdr.size_out) in the header between the two fetches because of a race condition, leading to severe kernel errors, such as buffer over-accesses. This bug can cause a local denial of service and information leakage.

The bug was discovered 05/14/2018. The weakness was presented 06/22/2018 (Website). The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2018-12633 since 06/21/2018. Local access is required to approach this attack. The successful exploitation requires a simple authentication. Technical details are known, but there is no available exploit.

The vulnerability was handled as a non-public zero-day exploit for at least 38 days. During that time the estimated underground price was around $0-$5k. The vulnerability scanner Nessus provides a plugin with the ID 110821 (Fedora 27 : kernel (2018-2a0f8b2c9d)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Fedora Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 277367 (Fedora Security Update for kernel (FEDORA-2018-2a0f8b2c9d)).

Upgrading eliminates this vulnerability. A possible mitigation has been published 2 weeks after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (110821).

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 4.17.0
• 4.17.1
• 4.17.2

License

• open-source

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CPE 2.2info

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