Is setuid dangerous?
setuid and setgid files are dangerous because they might give an unauthorized user root access, or at least access to run a program in another user’s name. To make a program setuid root, the user must be root. However, it is very difficult to be so sure, as hackers may have cracked root’s password.
What does setuid 0 mean?
SETUID 0 or root means that when the program is run it is as if root ran it – which leaves you open to all the usual security risks of running something at high permission levels – it could potentially do anything to your system – so generally the number of applications that require SETUID should be minimised on a Unix …
What is setuid executable?
Setuid, which stands for set user ID on execution, is a special type of file permission in Unix and Unix-like operating systems such as Linux and BSD. When an executable file’s setuid permission is set, users may execute that program with a level of access that matches the user who owns the file.
What are setuid binaries?
Binaries with the setuid bit enabled, are being executed as if they were running under the context of the root user. This enables normal (non-privileged) users to use special privileges, like opening sockets. While this seems unnecessary for a normal user, it is actually needed for simple commands like ping.
Is there a way to ignore the setuid bit?
For this reason, most unices ignore the setuid bit when they detect a shebang. One way to secure this implementation would be for the kernel to lock the script file until the interpreter has opened it (note that this must prevent not only unlinking or overwriting the file, but also renaming any directory in the path).
When to use the setuid and setgid permissions?
So, for example, if an executable has the setuid bit set on it, and it’s owned by root, when launched by a normal user, it will run with root privileges. It should be clear why this represents a potential security risk, if not used correctly.
How does scripting allow setuid on shell scripts?
Capabilities can optionally be inherited to sub-processes. Super allows specified users to execute scripts (or other commands) as if they were root; or it can set the uid, gid, and/or supplementary groups on a per-command basis before executing the command. It is intended to be a secure alternative to making scripts setuid root.
Can a attacker invoke a setuid script in Linux?
If setuid scripts are allowed with this implementation, an attacker can invoke an arbitrary script by creating a symbolic link to an existing setuid script, executing it, and arranging to change the link after the kernel has performed step 1 and before the interpreter gets around to opening its first argument.