CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
    As independent public accountants, we hereby consent to the incorporation by
reference in this Registration Statement on Form S-4 of UST Corp. of our reports
dated January 31, 1997 and January 26, 1996 relating to the consolidated
financial statements of Firestone Financial Corp., which appear in the Current
Report on Form 8-K of UST Corp. dated February 6, 1998. and to all references to
our firm included in this Registration Statement.
 
                                          ARTHUR ANDERSEN LLP
 
Boston, Massachusetts
February 5, 1998