![]() Watch what happens in this screenshot if we don’t first elevate our permissions with sudo. All your worst fears have come true, but all you needed to do was ask for permission! That’s why we want to remember to ask for superuser permissions upfront like this: sudo reboot That awesome source code you downloaded and need to compile wont. You might even be lucky enough to given an “Access Denied” or another friendly error message. It’s more of a dramatic story in Linux. Things might behave quite strangely without the proper permissions. The important config file you were editing may not save correctly. A program you installed may simply refuse to run. ![]() In Windows, if you try to perform an administrative task, a dialog box asks you if you wish to continue (“Are you really sure your want to run that program you just clicked on?”). The task is then performed. On a Mac, a security dialog box pops up and you are required to type in your password and click OK. You even need elevated privileges to shutdown or restart the computer. “Hey, who turned this thing off?!” If you’re familiar with Windows, it’s very similar to the Windows User Account Control dialog box that pops up when you try to do anything important, just not as friendly. Wiz empowers security teams to respond rapidly to the threat, and focus on the resources with the highest risk first.So, what is sudo for and what does it do? If you prefix “sudo” with any Linux command, it will run that command with elevated privileges. Elevated privileges are required to perform certain administrative tasks. Someday you may wish to run a LAMP (Linu Apache MySQL PHP) server, and will have to manually edit your config files. You might also have to restart or reset the Apache web server or other service daemons. Wiz can be deployed quickly, and instantly perform a cloud scan to identify all vulnerable Linux instances. This inconsistency is what makes the bug exploitable. Finally, the code that decides whether to remove the escape characters did not check whether a command is actually being run, just that the shell flag is set. Because a command is not actually being run, sudo does not escape special characters. However, due to a different bug, this time in the command line parsing code, it is possible to run sudoedit with either the -s or -i options, setting a flag that indicates shell mode is enabled. Under normal circumstances, this bug would be harmless since sudo has escaped all the backslashes in the command’s arguments. The sudoers policy plugin will then remove the escape characters from the arguments before evaluating the sudoers policy (which doesn’t expect the escape characters) if the command is being run in shell mode.Ī bug in the code that removes the escape characters will read beyond the last character of a string if it ends with an unescaped backslash character. When sudo runs a command in shell mode, either via the -s or -i command line option, it escapes special characters in the command’s arguments with a backslash. If the system is patched, it will respond with an error that starts with “usage:” If the system is vulnerable, it will respond with an error that starts with “sudoedit:” Test for the vulnerability yourself: To test if a system is vulnerable or not follow these steps: Versions released as far back as 2011 are affected by this vulnerability.Īll legacy versions from 1.8.2 to 1.8.31p2Īll stable versions from 1.9.0 to 1.9.5p1 With an estimated 90% of cloud workloads running Linux based OS, with sudo being common across distributions, many Linux cloud assets are at risk and may be affected. ![]() The affected versions are 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. Therefore, this vulnerability presents a major and immediate risk. The package sudo is a near universal utility across Linux distributions and flavors that manages local user privileges. ![]() ![]() A newly discovered high severity vulnerability (CVE-2021-3156) in the sudo package allows privilege escalation from any user to root without any authentication. ![]()
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