diagrpt in AIX 4.3.x and 5.1 uses the DIAGDATADIR environment variable to find and execute certain programs, which allows local users to gain privileges by modifying the variable to point to a Trojan horse program.
AIX sysback before 4.2.1.13 uses a relative path to find and execute the hostname program, which allows local users to gain privileges by modifying the path to point to a malicious hostname program.