Linux Kernel up to 4.7 setuid Program fs/binfmt_elf.c install_exec_creds race condition

Summaryinfo

A vulnerability was found in Linux Kernel up to 4.7. It has been classified as problematic. Impacted is the function install_exec_creds of the file fs/binfmt_elf.c of the component setuid Program Handler. This manipulation causes race condition. The identification of this vulnerability is CVE-2019-11190. The attack can only be executed locally. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Linux Kernel up to 4.7 (Operating System). It has been declared as problematic. Affected by this vulnerability is the function install_exec_creds of the file fs/binfmt_elf.c of the component setuid Program Handler. The manipulation with an unknown input leads to a race condition vulnerability. The CWE definition for the vulnerability is 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. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

The Linux kernel before 4.8 allows local users to bypass ASLR on setuid programs (such as /bin/su) because install_exec_creds() is called too late in load_elf_binary() in fs/binfmt_elf.c, and thus the ptrace_may_access() check has a race condition when reading /proc/pid/stat.

The bug was discovered 04/03/2019. The weakness was shared 04/12/2019 (Website). The advisory is shared at securityfocus.com. This vulnerability is known as CVE-2019-11190 since 04/11/2019. An attack has to be approached locally. The requirement for exploitation is a single authentication. Technical details are known, but no exploit is available.

The vulnerability was handled as a non-public zero-day exploit for at least 9 days. During that time the estimated underground price was around $0-$5k. The commercial vulnerability scanner Qualys is able to test this issue with plugin 197486 (Ubuntu Security Notification for Linux, Linux-aws, Linux-kvm, Linux-raspi2, Linux-snapdragon Vulnerabilities (USN-4008-1)).

Upgrading to version 4.8 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at SecurityFocus (BID 107890†). The entries VDB-82964, VDB-107092, VDB-115786 and VDB-131935 are related to this item. Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6
• 4.7

License

• open-source

Website

• Vendor: https://www.kernel.org/

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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