Unixware's security model includes the concept of privileges. These can be assigned to processes and allow them to perform tasks that otherwise could only be performed by the root user. They allow programs to run with the minimum required privilege (as opposed to running as root). A vulnerability in Unixware's implementation of privileges allows regular users to attach a debugger to a running privileged program and take over its privileges. Most Unix systems, including Uniware, place a number of restriction on how can regular users interact with setuid and setgid processes. For example they are not allowed to attach a debugger to them and the dynamic linker may ignore variables requesting the preloading of some shared libraries. Unixware's implementation of privileges provides no such protections for privileged programs allowing a user to attach a debugger to a running privileged program which has his same user uid and modifying it. When a program that is listed in the...
Unixware's security model includes the concept of privileges. These can be assigned to processes and allow them to perform tasks that otherwise could only be performed by the root user. They allow programs to run with the minimum required privilege (as opposed to running as root). A vulnerability in Unixware's implementation of privileges allows regular users to attach a debugger to a running privileged program and take over its privileges. Most Unix systems, including Uniware, place a number of restriction on how can regular users interact with setuid and setgid processes. For example they are not allowed to attach a debugger to them and the dynamic linker may ignore variables requesting the preloading of some shared libraries. Unixware's implementation of privileges provides no such protections for privileged programs allowing a user to attach a debugger to a running privileged program which has his same user uid and modifying it. When a program that is listed in the /etc/security/tcb/privs is executed it is granted the privileges listed there. All a malicious has to do to exploit the problem is find a program listed in that file with the privileges it wishes to gain and executable by him. Example of programs executable by anyone with privileges include: /usr/ucb/w (DACREAD), /usr/bin/getdev (DACWRITE), and /usr/ucb/lpr (SETUID).
