WS_FTP Server is reported prone to a remote denial of service vulnerability. This issue presents itself when the application processes a malformed file path through the 'cd' command.
WS_FTP Server version 5.0.2 is reported prone to this issue, however, other versions may be affected as well.
Connected to ibm.
220-ibm X2 WS_FTP Server 5.0.2.EVAL (106633167)
220-Fri Aug 27 14:12:19 2004
220-29 days remaining on evaluation.
220 ibm X2 WS_FTP Server 5.0.2.EVAL (106633167)
User (ibm:(none)): ftp
331 Password required
230 user logged in
ftp> cd a../a
Connection closed by remote host.
WS_FTP Server version contains a flaw that may allow a remote denial of service. The issue is triggered in the file path parse module which will cause the FTP server to consume large amounts of CPU power. When this occurs, it will result in loss of availability for the service.
Currently, there are no known upgrades or patches to correct this issue. It is possible to correct the flaw by implementing the following workaround: Restrict access to the FTP server and disallow anonymous usage.