What do the permissions -rwSr-xr-x mean for a binary file when it is executed as a command?
What do the permissions -rwSr-xr-x mean for a binary file when it is executed as a command?
The permissions -rwSr-xr-x indicate that the command is SetUID and will be executed with the effective rights of the owner. The 'S' in place of the owner's execute bit means that the SetUID bit is set, but the owner does not have execute permission. This setting allows the file to run with the privileges of the owner, not the person running the command. Therefore, the SetUID permission means the command will execute with the owner's rights, making option A correct.
The correct answer is: C. The execute flag is not set for the owner. Therefore the SetUID flag is ignored. Here's a more detailed explanation: SetUID (Set User ID): This bit allows a file to be executed with the permissions of the file owner, rather than the permissions of the user executing it. However, for this to work, the file must also have the execute permission set for the owner. Execute Permission: This permission allows a file to be executed as a program. In the given permissions (-rwSr-xr-x), the execute permission is not set for the owner (indicated by the hyphen in the first position). Therefore, even though the SetUID bit is set (indicated by the 'S'), the command will not be executed with the effective rights of the owner. It will be executed with the permissions of the user who runs it.
C. The execute flag is not set for the owner. Therefore the SetUID flag is ignored. The S in the permissions indicates that the execute bit is not set; therefore, even though the SetUID bit is present, it will not have any effect when the command is executed.
The permissions -rwSr-xr-x for a binary file mean that the command is SetUID and it will be executed with the effective rights of the owner. The capital "S" in the permissions indicates that the SetUID bit is set, which means that when the binary file is executed, it will run with the permissions of the owner of the file, rather than the permissions of the user executing the command. The lowercase "s" in the permissions indicates that the SetGID bit is set, but since it is in the "others" category, it does not apply here. The x flag is set for the group and others, which means that they have execute permission for the file. However, the owner of the file does not have execute permission, which means that they cannot execute the file directly, but they can still execute it through the SetUID mechanism.
Option B is not correct because the group does not have any special permission set (e.g., SetGID bit is not set), and even if it had, it would not affect the SetUID bit. The SetUID bit only affects the permissions of the owner of the file, not the group. Option C is not correct because even though the execute flag is not set for the owner, the SetUID bit is still honored when the file is executed. The SetUID bit overrides the lack of execute permission for the owner. Option D is not correct because the group does not have any special permission set that would allow it to execute the file with elevated permissions. The command will only be executed with the effective rights of the owner due to the SetUID bit.