Symlink_race
Symlink race
Software Security
A symlink race is a kind of software security vulnerability that results from a program creating files in an insecure manner.[1] A malicious user can create a symbolic link to a file not otherwise accessible to them. When the privileged program creates a file of the same name as the symbolic link, it actually creates the linked-to file instead, possibly inserting content desired by the malicious user (see example below), or even provided by the malicious user (as input to the program).
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It is called a "race" because in its typical manifestation, the program checks to see if a file by that name already exists; if it does not exist, the program then creates the file. An attacker must create the link in the interval between the check and when the file is created.
A symlink race can happen with antivirus products that decide they will quarantine or delete a suspicious file, and then go ahead and do that. During the interval between decision and action, malicious software can replace the suspicious file with a system or antivirus file that the malicious software wants overwritten.[2]