Provide the root password when prompted and hit ENTER to gain access to the server. Step 1: Log in to your serverįirst, log in to your cloud server as the root user using the syntax shown. To create a sudo user on Ubuntu 20.04, follow the steps outlined. We will cover these scenarios in depth later on in this guide.įirst, we will walk you through the creation of a sudo user on Ubuntu 20.04. In addition, you can configure sudo to restrict a sudo user to a handful of commands or allow them to run all commands as the root user. A sudo user is, therefore, a regular Linux user with elevated privileges to run commands as a root user or another regular user, the default being the root user. Sudo is a program that grants regular users permissions to run commands with root privileges or as another user. Since administering the Linux system as the root user is highly discouraged, a system administrator needs to grant a regular user some level of privilege to execute some (or all) root commands. For this reason, it’s always recommended to run commands as a sudo user. It only takes one wrong command to crash the system. The root user can also break the system, whether intentionally or accidentally – which is why it’s not recommended to log in and run the system as the root user. This includes installing and uninstalling programs, accessing and modifying system files, and customizing the system. The root user is an administrative user with the highest privileges and is not bound by any permission restrictions. One unique user in the Linux system is the root user. If you own a file or a directory, you can pretty much do anything you want with it – you can access it, edit it, rename and even delete it.īut not all users are the same. These permissions determine access rights or privileges that users have on the file. By default, each file in Linux has its own permissions and directories. This oversimplification then leads us to the concept of file permissions and directories. These entities are represented by a file descriptor which is a unique identifier for a file or other resources such as directories, network sockets, or processes – hence the concept “everything is a file”. It implies that in a Linux system, every single entity is considered a file. The oversimplification simply gives a high-level overview of the Linux architecture. We have directories, symbolic links, processes, pipes, and sockets just to mention a few. This sounds somewhat puzzling since the Linux system comprises various entities and not just files. Other operating systems and distributions are also likely to be exploitable.Īs soon as the Qualys research team confirmed the vulnerability, Qualys engaged in responsible vulnerability disclosure and coordinated with sudo’s author and open source distributions to announce the vulnerability.You probably have heard of the concept “In Linux, everything is a file”. Qualys security researchers have been able to independently verify the vulnerability and develop multiple variants of exploit and obtain full root privileges on Ubuntu 20.04 (Sudo 1.8.31), Debian 10 (Sudo 1.8.27), and Fedora 33 (Sudo 1.9.2). Successful exploitation of this vulnerability allows any unprivileged user to gain root privileges on the vulnerable host. It was introduced in July 2011 (commit 8255ed69) and affects all legacy versions from 1.8.2 to 1.8.31p2 and all stable versions from 1.9.0 to 1.9.5p1 in their default configuration. The vulnerability itself has been hiding in plain sight for nearly 10 years. It allows users to run programs with the security privileges of another user. Sudo is a powerful utility that’s included in most if not all Unix- and Linux-based OSes. Any unprivileged user can gain root privileges on a vulnerable host using a default sudo configuration by exploiting this vulnerability. Original Post: The Qualys Research Team has discovered a heap overflow vulnerability in sudo, a near-ubiquitous utility available on major Unix-like operating systems. Qualys has not independently verified the exploit. Solaris are also vulnerable to CVE-2021-3156, and that others may also Update Feb 3, 2021: It has been reported that macOS, AIX, and
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