Prevent changing DACL by SetSecurityInfo

Hello,

my service creates a Named Pipe with SECURITY_ATTRIBUTES (DACL) which
limit the access to SID of the active user. Is it possible that
another program change the DACL of the Named Pipe that everyone have
access?
How can I prevent this?
Thanks for your help!

Mario


My DACL is:
"D:"+SDDL_PROTECTED // Discretionary ACL
"(D;OICI;GA;;;BG)" // Deny access to built-in guests
"(D;OICI;GA;;;AN)" // Deny access to anonymous logon
"(A;OICI;GRGW;;;%%AvtiveUserSid%%)"

Does I have to add "(A;OICI;GRGWGX;;;CO)" // Allow read/write/execute
to creator/owner?

.