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                                SECOND AMENDMENT
                                       TO
                          SHAREHOLDER RIGHTS AGREEMENT

                                 March 29, 2001

         Second Amendment to that certain Shareholder Rights Agreement, (the
"Agreement"), made as of October 21, 1999 and amended as of January 4, 2000,
between CORE, INC., a Massachusetts corporation (the "Company"), and State
Street Bank and Trust Company, a Massachusetts chartered trust company (the
"Rights Agent").

         Capitalized terms used herein and not otherwise defined will have the
meanings ascribed to them in the Agreement.

         WHEREAS, pursuant to the provisions of Section 27 of the Agreement,
prior to the occurrence of a Section 11(a)(ii) Event, the Company and the Rights
Agent shall, if the Board of Directors of the Company so directs, supplement or
amend any provision of this Agreement as the Board of Directors of the Company
may deem necessary or desirable without the approval of any holders of
certificates representing shares of Common Stock of the Company;

         WHEREAS, as of the date hereof there has not occurred a Section
11(a)(ii) Event;

         WHEREAS, the Company and Fortis, Inc. ("Fortis") have, as of the date
hereof, entered into an Agreement and Plan of Merger (the "Merger Agreement"),
providing for the acquisition by Fortis of all of the outstanding Common Stock
of the Company;

         WHEREAS, on March 29, 2001, the Board of Directors of the Company voted
to amend the Agreement to exempt from the provisions of the Agreement, the
execution of the Merger Agreement and the acquisition and ownership of shares of
the Common Stock of the Company by Fortis or any of its Affiliates or Associates
pursuant to the Merger Agreement so that, as a result of the actions to be taken
pursuant to the terms of the Merger Agreement, no Distribution Date or Section
11(a)(ii) Event will occur under the Agreement;

         NOW, THEREFORE, pursuant to the provisions of Section 27 of the
Agreement, the Company and the Rights Agent hereby agree as follows:

         1. The Agreement is hereby amended so that Fortis shall be deemed to be
a "Grandfathered Person" under the Agreement. In furtherance thereof, the
Company and the Rights Agent hereby amend SECTION 1(q) of the Agreement so that,
as amended, it shall read in its entirety as follows:

         "(q) "GRANDFATHERED PERSON" shall mean any of (i) Gilder Gagnon Howe &
         Co., LLC, (ii) Warburg, Pincus Asset Management, Inc., (iii) Gagnon
         Securities (PROVIDED, HOWEVER, that any Affiliate or Associate of
         Gagnon


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         Securities shall be deemed to be a Grandfathered Person only
         during such time as such Person continues to be an Affiliate or
         Associate of Gagnon Securities) or (iv) Fortis, or any of their
         respective Affiliates or Associates."

         2. The Agreement is hereby amended so that the "Grandfathered
Percentage" of Fortis under the Agreement shall be all shares of Common Stock of
the Company acquired by Fortis or any of its Affiliates or Associates pursuant
to the terms of the Merger Agreement. In furtherance thereof, the Company and
the Rights Agent hereby amend SECTION 1(p) of the Agreement so that, as amended,
it shall read in its entirety as follows:

         "(p) "GRANDFATHERED PERCENTAGE" shall mean, (i) with respect to any
         Grandfathered Person, other than Gagnon Securities or Fortis or any of
         their respective Affiliates or Associates, the percentage of the
         outstanding shares of Common Stock that such Grandfathered Person,
         together with all Affiliates and Associates of such Grandfathered
         Person, beneficially owns as of the Grandfathered Time plus an
         additional two percent (2%); (ii) with respect to Gagnon Securities or
         any of its Affiliates or Associates, twenty (20%) percent of the
         outstanding shares of Common Stock of the Company; and (iii) with
         respect to Fortis or any of its Affiliates or Associates, all of the
         shares of Common Stock of the Company acquired by Fortis or any of its
         Affiliates or Associates pursuant to the terms of the Merger Agreement;
         provided, however, that, in the event any Grandfathered Person other
         than Gagnon Securities or any of its Affiliates or Associates shall
         sell, transfer, or otherwise dispose of any outstanding shares of
         Common Stock after the Grandfathered Time, the Grandfathered Percentage
         shall, subsequent to such sale, transfer or disposition, mean, with
         respect to such Grandfathered Person, the lesser of (i) the
         Grandfathered Percentage as in effect immediately prior to such sale,
         transfer or disposition or (ii) the percentage of outstanding shares of
         Common Stock that such Grandfathered Person beneficially owns
         immediately following such sale, transfer or disposition plus an
         additional two percent (2%)."

         3. The Agreement is hereby amended to provide for the continuation of
Fortis' status as a Grandfathered Person under certain circumstances. In
furtherance thereof, the Company and the Rights Agent hereby amend SECTION 1(a)
of the Agreement by striking the final sentence of the first paragraph of
SECTION 1(a) and replacing it with the following sentence:

         "Any Grandfathered Person who after the Grandfathered Time becomes the
         Beneficial Owner of less than 15% of the shares of Common Stock of the
         Company then outstanding shall cease to be a Grandfathered Person;
         PROVIDED, HOWEVER, that the provisions of this sentence shall not apply
         to Gagnon Securities or Fortis or any of their respective Affiliates or
         Associates."

         4. Except as otherwise expressly provided herein, all provisions of the
Agreement shall remain in full force and effect.


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<PAGE>

         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed as an instrument under seal and attested, all as of the day and
year first above written.

Attest:                                     CORE, INC.



By: /s/ Stephen M. Kane              By: /s/ George C. Carpenter Iv
   ---------------------------          ---------------------------
    Stephen M. Kane                  Name: George C. Carpenter Iv
                                           ----------------------
     Assistant Clerk                 Title: Chairman and Chief Executive Officer
                                            ------------------------------------


Attest:                              STATE STREET BANK AND
                                     TRUST COMPANY, as rights agent



By: /s/ [ILLEGIBLE]                   By: /s/ Charles Rossi
   ---------------------------          ----------------------------------------
                                     Name: Charles Rossi
                                          --------------------------------------
                                     Title: Division President
                                           -------------------------------------


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