source: https://www.securityfocus.com/bid/9733/info

It has been reported that Apache may be prone to a directory traversal vulnerability that may allow a remote attacker to access information outside the server root directory. This issue is only reported to present itself in Apache running on cygwin platforms. A remote attacker may traverse outside the server root directory by using encoded '\..' character sequences.

http://www.example.com/%5c%2e%2e%5c%2e%2e%5c%2e%2e%5c%2e%2e%5cboot.ini
http://www.example.com/..%5C..%5C..%5C..%5C..%5C..%5C/boot.ini