CVE-2019-14287
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Description
A flaw was found in the way sudo implemented running commands with arbitrary user ID. If a sudoers entry is written to allow the attacker to run a command as any user except root, this flaw can be used by the attacker to bypass that restriction.
Statement
This flaw only affects specific, non-default configurations of sudo, in which sudoers configuration entry allows a user to run a command as any user except root, for example:
someuser myhost = (ALL, !root) /usr/bin/somecommand
This configuration allows user "someuser" to run somecommand as any other user except root. However, this flaw also allows someuser to run somecommand as root by specifying the target user using the numeric id of -1. Only the specified command can be run, this flaw does NOT allow user to run other commands that those specified in the sudoers configuration.
Any other configurations of sudo (including configurations that allow user to run commands as any user including root and configurations that allow user to run command as a specific other user) are NOT affected by this flaw.
Red Hat Virtualization Hypervisor includes an affected version of sudo, however the default configuration is not vulnerable to this flaw.
Mitigation
This vulnerability only affects configurations of sudo that have a runas user list that includes an exclusion of root. The most simple example is:
someuser ALL=(ALL, !root) /usr/bin/somecommand
The exclusion is specified using an excalamation mark (!). In this example, the "root" user is specified by name. The root user may also be identified in other ways, such as by user id:
someuser ALL=(ALL, !#0) /usr/bin/somecommand
or by reference to a runas alias:
Runas_Alias MYGROUP = root, adminuser
someuser ALL=(ALL, !MYGROUP) /usr/bin/somecommand
To ensure your sudoers configuration is not affected by this vulnerability, we recommend examining each sudoers entry that includes the `!` character in the runas specification, to ensure that the root user is not among the exclusions. These can be found in the /etc/sudoers file or files under /etc/sudoers.d.
Additional information
- Bugzilla 1760531: sudo: Privilege escalation via 'Runas' specification with 'ALL' keyword
- CWE-267: Privilege Defined With Unsafe Actions
- FAQ: Frequently asked questions about CVE-2019-14287
Common Vulnerability Scoring System (CVSS) Score Details
Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
| Red Hat | NVD | |
|---|---|---|
CVSS v3 Base Score | 7 | 8.8 |
Attack Vector | Local | Network |
Attack Complexity | High | Low |
Privileges Required | Low | Low |
User Interaction | None | None |
Scope | Unchanged | Unchanged |
Confidentiality Impact | High | High |
Integrity Impact | High | High |
Availability Impact | High | High |
CVSS v3 Vector
Red Hat: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Acknowledgements
Red Hat would like to thank the Sudo project for reporting this issue. Upstream acknowledges Joe Vennix (Apple Information Security) as the original reporter.
Frequently Asked Questions
Why is Red Hat's CVSS v3 score or Impact different from other vendors?
For more information, see https://access.redhat.com/solutions/762393.
My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?
- "Under investigation" doesn't necessarily mean that the product is affected by this vulnerability. It only means that our Analysis Team is still working on determining whether the product is affected and how it is affected.
- "Affected" means that our Analysis Team has determined that this product is affected by this vulnerability and might release a fix to address this in the near future.
What can I do if my product is listed as "Will not fix"?
Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
- Upgrade to a supported product version that includes a fix for this vulnerability (recommended).
- Apply a mitigation (if one exists).
- Open a support case to request a prioritization of releasing a fix for this vulnerability.
What can I do if my product is listed as "Fix deferred"?
Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
- Apply a mitigation (if one exists).
- Open a support case to request a prioritization of releasing a fix for this vulnerability.
- Red Hat Engineering focuses on addressing high-priority issues based on their complexity or limited lifecycle support. Therefore, lower-priority issues will not receive immediate fixes.
What is a mitigation?
I have a Red Hat product but it is not in the above list, is it affected?
Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?
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