#Filesafe temporary acess code password
Access to the password file was restricted, so the attacker could not write to it. The attacker would write a script that made repeated guesses on the temporary filename used and create a symbolic link from that name to the password file. There is a famous example, reported in, of some versions of the tripwire file integrity program9 suffering from this bug. This is another example of a race condition, very similar to that when two processes race to access a shared file when locks are not used. The attacker then attempts to create a file with that name in the interval between the program checking the file does not exist and subsequently creating it. The attacker could attempt to guess the temporary filename a privileged program will use. This approach suffices from the perspective of reliability but not with respect to security.Īgain the problem is that an attacker does not play by the rules. The program generally checks to ensure that the file does not already exist, perhaps left over from a crash of a previous program, then creates the file. As each process has its own distinct identifier, this should guarantee a unique name.
The most common technique for constructing a temporary filename is to include a value such as the process identifier. In a sense, this is the opposite problem to managing access to a shared file. The critical issue with temporary files is that they are unique and not accessed by other processes. Most operating systems provide well-known locations for placing temporary files and standard functions for naming and creating them.
A temporary file is commonly used for this purpose. Many programs need to store a temporary copy of data while they are processing the data.
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