Updated rsh packages that fix various bugs and a theoretical security issue are now available. This update has been rated as having low security impact by the CentOS Security Response Team
The rsh package contains a set of programs that allow users to run commands on remote machines, login to other machines, and copy files between machines, using the rsh, rlogin, and rcp commands. All three of these commands use rhosts-style authentication. The rcp protocol allows a server to instruct a client to write to arbitrary files outside of the current directory. This could potentially cause a security issue if a user uses rcp to copy files from a malicious server. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CAN-2004-0175 to this issue. These updated packages also address the following bugs: The rexec command failed with "Invalid Argument", because the code used sigaction() as an unsupported signal. The rlogind server reported "SIGCHLD set to SIG_IGN but calls wait()" message to the system log because the original BSD code was ported incorrectly to linux. The rexecd server did not function on systems where client hostnames were not in the DNS service, because server code called gethostbyaddr() for each new connection. The rcp command incorrectly used the "errno" variable and produced erroneous error messages. The rexecd command ignored settings in the /etc/security/limits file, because the PAM session was incorrectly initialized. The rexec command prompted for username and password regardless of the ~/.netrc configuration file contents. This updated package contains a patch that no longer skips the ~/.netrc file. All users of rsh should upgrade to these updated packages, which resolve these issues.