Open iim.conf.
See iim.conf File Syntax for instructions on locating and modifying iim.conf.
Modify the iim_ldap.usergroupbynamesearchfilter attribute.
This parameter specifies the LDAP search string used when searching for users or groups. Provide the attribute value in standard LDAP filter syntax. You can modify it to allow more complex searches. See your Directory Server documentation for more information on modifying search strings.
Save and close the file.