Emergency fixes are available via anonymous ftp. Information on obtaining and using FixDist is available on the Internet. Although AIX is likely no more or less vulnerable to this type of attack than any other vendor, IBM does recommend the following fixes to harden your AIX system against external TCP protocol attacks. The APAR numbers for the fixes are given below. AIX is vulnerable to this problem.
Fixes are in process.
The APAR numbers for the fixes are given below. IBM has incorporated options into sendmail that disable the VRFY and EXPN features of sendmail. Use the '-o' parameter on the command line or the O control line in the configuration file to activate these options. When enabled, this option disables the VRFY and EXPN commands. These commands are required and do run, but they echo their argument back to the user rather than expanding the argument to indicate whether it is valid or invalid.