How to unzip CAB file with ActiveX on unix system?
There is no built-in tool to handle CAB; it's not a standard or Unix file format. As Mike said, you'll probably need cabextract. There are some packages that might be of use depending on what version of AIX you are running.
Otherwise you will need to compile it. If you don't have the AIX compiler, you'll have to install GCC.
(What a sad and user-hostile place Old Unix was before Linux; it's pretty damned pathetic if compilers are still paid extras.)