Under certain circumstances, sudo could be made to run programs without a password.
Alexander Kurtz discovered that sudo would not prompt for a password when a group was specified in the Runas_Spec. A local attacker could exploit this to execute arbitrary code as the specified group if sudo was configured to allow the attacker to use a program as this group. The group Runas_Spec is not used in the default installation of Ubuntu.
20 January 2011
A security issue affects these releases of Ubuntu and its derivatives:
Under certain circumstances, sudo could be made to run programs without a password.
Alexander Kurtz discovered that sudo would not prompt for a password when a group was specified in the Runas_Spec. A local attacker could exploit this to execute arbitrary code as the specified group if sudo was configured to allow the attacker to use a program as this group. The group Runas_Spec is not used in the default installation of Ubuntu.
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
In general, a standard system update will make all the necessary changes.