A new vulnerability allows a low-privileged user account on most Linux operating systems with UID value greater than 2147483647 to execute any systemctl command.
PUBLISH DATE: 10-DECEMBER-2018
A flaw was found in PolicyKit in Linux (aka polkit) 0.115 that allows a user with a UID greater than INT_MAX to successfully execute any systemctl command, which means privilege escalation.
The vulnerability is reported to be in PolicyKit, an application-level toolkit for Unix-like operating systems that defines policies, handles system privileges and serves as communication medium between non-privileged and privileged processes.
PolicyKit’s improper validation of permission requests for any low-privileged user with UID greater than INT_MAX results in this flaw. INT_MAX is a constant in computer programming that defines what maximum value an integer variable can store, which equals to 2147483647 (in hexadecimal 0x7FFFFFFF).
Thus, a user account created on an affected Linux system with any UID greater than INT_MAX value will be allowed by the PolicyKit to successfully execute any systemctl command.
PolicyKit version 0.115
(It’s preinstalled on most popular Linux distributions)
The flaw is fixed in versions policykit-1/0.105-18+deb9u1, policykit-1/0.105-23, policykit-1/0.115-3.
Upgrade your policykit-1 packages.
It is also recommended that system administrators should not allow any negative UIDs or UIDs greater than 2147483646 in order to avoid falling victim to this vulnerability.
If you think you are a victim of a cyber-attack, immediately send an e-mail to firstname.lastname@example.org.