<PAGE>   1
                                                                  EXHIBIT 10.12

                              EMPLOYMENT AGREEMENT

            THIS AGREEMENT is entered into as of December 9, 1999, by and
between ANU SHUKLA (the "Employee") and BROADBASE SOFTWARE, INC., a Delaware
corporation (the "Company"). This Agreement shall be effective at the effective
time of the merger (the "Merger") contemplated by the Merger Agreement and Plan
of Reorganization dated December 9, 1999, by and among the Company, Rubric,
Inc., a Delaware corporation ("Rubric") and Bronco Acquisition Corp., a Delaware
Corporation and a wholly owned subsidiary of the Company. This Agreement shall
be null and void, and no parties shall be deemed to have any rights hereunder,
unless and until the Merger is consummated.

            1. DUTIES AND SCOPE OF EMPLOYMENT.

                  (a) POSITION. The Company agrees to employ the Employee in an
executive advisory position and the Employee shall report to the Company's
President. Employment of Employee will commence on the effective date of the
Merger.

                  (b) OBLIGATIONS TO THE COMPANY. During her Employment, the
Employee shall devote her full business efforts and time to the Company. During
her Employment, without the prior written approval of the Company's Board of
Directors, the Employee shall not render services in any capacity to any other
person or entity and shall not act as a sole proprietor or partner of any other
person or entity or as a shareholder owning more than five percent of the stock
of any other corporation. The Employee shall comply with the Company's policies
and rules, as they may be in effect from time to time during her Employment.

                  (c) NO CONFLICTING OBLIGATIONS. The Employee represents and
warrants to the Company that she is under no obligations or commitments, whether
contractual or otherwise, that are inconsistent with her obligations under this
Agreement. The Employee represents and warrants that she will not use or
disclose, in connection with her employment by the Company, any trade secrets or
other proprietary information or intellectual property in which the Employee or
any other person has any right, title or interest and that to the best of her
knowledge her employment by the Company as contemplated by this Agreement will
not infringe or violate the rights of any other person. The Employee represents
and warrants to the Company that she has returned all property and confidential
information belonging to any prior employer.

            2. SALARY. The Company shall pay the Employee as compensation for
her services a base salary at a gross annual rate of not less than $195,000.
Such salary shall be payable in accordance with the Company's standard payroll
procedures. Employee will be eligible for a target bonus of $15,000 pursuant to
the Company's bonus plan.
<PAGE>   2
            3. VACATION AND EMPLOYEE BENEFITS. During her Employment, the
Employee shall be eligible for paid vacations in accordance with the Company's
standard policy for similarly-situated executive employees, as it may be amended
from time to time. During her Employment, the Employee shall be eligible to
participate in the employee benefit plans maintained by the Company for
similarly-situated executive employees, subject in each case to the generally
applicable terms and conditions of the plan in question and to the
determinations of any person or committee administering such plan. Promptly
after the effective date of the Merger, Broadbase shall execute an
indemnification agreement for Employee consistent with indemnification
agreements provided to other directors and officers of Broadbase.

            4. BUSINESS EXPENSES. During her Employment, the Employee shall be
authorized to incur necessary and reasonable travel, entertainment and other
business expenses in connection with her duties hereunder. The Company shall
reimburse the Employee for such expenses upon presentation of an itemized
account and appropriate supporting documentation, all in accordance with the
Company's generally applicable policies.

            5. EQUITY AWARDS.

                  (a) SHARES OF THE COMPANY. Notwithstanding any provision in
any plan, employment agreement, offer letter or other agreement between Employee
and Rubric ("Prior Agreements") to the contrary, all of the Employee's remaining
unreleased/unvested shares of Rubric common stock that are exchanged for shares
of Common Stock of the Company on the date of the Merger ("Restricted Shares")
shall remain unreleased/unvested until the date six (6) months following the
date of the Merger, at which time the Restricted Shares shall be fully
released/vested if Employee has been continuously employed by the Company since
the Merger, unless the Employee is terminated by the Company other than for
"cause" (as defined in Section 6(d) below), becomes permanently disabled, or
dies in which case all Restricted Shares shall be fully released/vested on the
date of (i) the Employee's termination of service, (ii) permanent disability, or
(iii) death. Employee agrees to cancel any right that Employee had to
accelerated release/vesting of the Restricted Shares as a result of any Prior
Agreements. Any portion of the Restricted Shares that are not released/vested
pursuant to this Section 5(a) shall be forfeited.

                  (b) STOCK OPTION. Immediately prior to the Merger, subject to
the approval of the Rubric Board of Directors, Rubric shall grant Employee a
stock option to purchase 150,000 shares of Common Stock of Rubric (the "New
Option") pursuant to the 1997 Rubric Stock Option Plan. To the extent that
options available for grant under the 1997 Rubric Stock Option Plan are
insufficient immediately prior to the Merger to grant the New Option in full
(any such shortfall in the shares under the New Option hereinafter termed the
"Shortfall Shares"), Broadbase agrees to grant Employee an option pursuant to
Broadbase's then current employee incentive stock option plan to purchase a
number of shares of Common Stock of Broadbase equal to the Shortfall Shares
multiplied by the Applicable Number as defined in section 1.1.4 of the Merger
Agreement. The New Option shall vest and become exercisable with respect to 12 _
% of the shares on the six month anniversary of the Merger and with respect to
an additional 2.0833% of the shares on the last day of each month thereafter
provided Employee continues to be employed by the Company. Notwithstanding any
provision of any Prior Agreement to the contrary, no acceleration of vesting or
exercisability shall occur as a result of


                                       2
<PAGE>   3
or related to the Merger. The additional terms of the New Option shall be set
forth in a standard stock option agreement pursuant to the relevant stock option
plan(s).

                  (c) RESTRICTION ON SALE OF SHARES. Employee agrees that
Employee will not, directly or indirectly, offer, sell, pledge, contract to sell
(including any short sale), grant any option to purchase or otherwise dispose of
any shares of common stock of the Company ("Dispositions") for a period of six
months following the Merger, to the extent that the aggregate of such
Dispositions would exceed 25% of the Applicable Shares; provided, however, that
this 25% restriction shall not apply to or take into account those shares of
Common Stock of the Company that Employee is permitted to sell and sells, with
Company's consent, in a public offering of the shares of common stock of the
Company. For purposes of this Section 5(c), "Applicable Shares" means the total
number of shares of common stock or options to purchase common stock of the
Company, both vested and unvested, held by the Employee on the date of the
Merger less the number of such shares of common stock of the Company that
Employee is permitted to sell and sells in a public offering of the shares of
common stock of the Company after the date of the Merger.

            6. TERM OF EMPLOYMENT.

                  (a) EMPLOYMENT AT WILL. Either party may terminate the
Employee's Employment at any time and for any reason (or no reason), and with or
without Cause, by giving the other party 30 days of notice in writing. The
Employee's Employment with the Company shall be "at will," meaning that either
the Employee or the Company shall be entitled to terminate the Employee's
employment at any time and for any reason, with or without Cause. Any contrary
representations that may have been made to the Employee shall be superseded by
this Agreement. This Agreement shall constitute the full and complete agreement
between the Employee and the Company on the "at will" nature of the Employee's
Employment, which may only be changed in an express written agreement signed by
the Employee and a duly authorized officer of the Company.

                  (b) RIGHTS UPON TERMINATION OF EMPLOYMENT. Upon the
termination of the Employee's Employment pursuant to this Section 6, the
Employee shall only be entitled to the compensation, benefits and reimbursements
described in Sections 2, 3, 4, 5 and 6 for the period preceding the effective
date of the termination. The payments under this Agreement shall fully discharge
all responsibilities of the Company to the Employee.

                  (c) TERMINATION OF AGREEMENT. This Agreement shall terminate
when all obligations of the parties hereunder have been satisfied. The
termination of this Agreement shall not limit or otherwise affect any of the
Employee's obligations under Sections 8 and 9.

                  (d) CASH SEVERANCE. Notwithstanding the foregoing, if
Employee's agreement is terminated other than for "cause" within six months of
the Merger, Employee shall be entitled to three (3) months base salary payable
in one lump sum. The term "Cause" shall mean:

            (i) Any breach of this Agreement between the Employee and the
      Company, or any other written agreement between the


                                       3
<PAGE>   4
      Employee and the Company, if such breach causes material harm to the
      Company;

                        (ii) Any willful misconduct that causes material harm to
      the Company, including (without limitation) repeated failure to follow the
      directions of the person to whom the Employee reports following a written
      warning, delivered to the Employee, of failure to follow such directions;

                        (iii) Conviction of, or a plea of "guilty" or "no
      contest" to, a felony under the laws of the United States or any state
      thereof;

                        (iv) Misappropriation of the assets of the Company or
      other acts of fraud or embezzlement; or

                        (v) The abuse of alcohol or controlled substances that
      has a detrimental effect upon the Employee's performance of her duties
      under this Agreement.

                  (e) RELEASE. Subsection (d) above shall not apply unless the
Employee (i) has executed a general release (in a form prescribed by the
Company) of all known and unknown claims that he may then have against the
Company or persons affiliated with the Company and (ii) has agreed not to
prosecute any legal action or other proceeding based upon any of such claims.

            7. NON-DISCLOSURE. This Agreement is contingent upon the Employee's
execution of the Company's form of Proprietary Information and Inventions
Agreement, a copy of which is attached hereto as EXHIBIT A.

            8. NON-COMPETITION, NON-SOLICITATION AND SAVINGS CLAUSE.

                  (a) THE RESTRICTED PERIOD. This Section 8 shall apply only
during the period commencing at the effective time of the Merger and ending on
the later to occur of: (i) the date 12 months from the Merger, or (ii) the
termination of the Employee's Employment for any reason (the "Restricted
Period").

                  (b) NON-COMPETITION AND NON-SOLICITATION. In exchange for the
consideration stated herein and for the purchase of her shares of Rubric stock
by the Company, the Employee agrees that during the Restricted Period he shall
not:

                        (i) Directly or indirectly, individually or in
      conjunction with others, engage in activities that competes with the
      Company's Business or work for any entity engaged in a business that
      competes with the Company's Business. The Employee in particular agrees
      not to solicit, serve, contract with or otherwise engage any existing or
      prospective customer, client or account of the Company that Employee
      directly or indirectly had contact with while employed by the Company.


                                       4
<PAGE>   5
                        (ii) Cause or attempt to cause any existing or
      prospective customer, client or account of the Company that Employee
      directly or indirectly had contact with while employed by the Company to
      divert from, terminate, limit or in any manner modify, or fail to enter
      into, any actual or potential business relationship with the Company. The
      Employee and the Company agree that this provision is reasonably enforced
      with reference to any geographic area in which the Company maintains any
      such relationship.

                        (iii) Directly or indirectly solicit, employ or conspire
      with others to employ any of the Company's employees. The term "employ"
      for purposes of this paragraph (iii) means to enter into an arrangement
      for services as a full-time or part-time employee, independent contractor,
      agent or otherwise. The Employee and the Company agree that this provision
      is reasonably enforced as to any geographic area in which the Company
      conducts its Business.

            The Employee further agrees that during the Restricted Period he
shall inform any new employer, or any other person or entity with whom he enters
into a business relationship, of the existence of this Section 8 before
accepting employment or entering into such business relationship. Ownership of
less than 5% of the outstanding stock of any corporation will not constitute a
violation of this Section.

            (c) DEFINITION OF BUSINESS. For purposes of this Agreement, the term
"Business" shall mean the development, marketing and/or sales of e-marketing,
analytic applications and CRM analysis software, including any of the following
features:

      (i)   automated execution of targeted and personalized Internet or
            traditional marketing campaigns

      (ii)  planning, execution, and real-time closed loop measurement of
            Internet or traditional marketing campaigns

      (iii) segmentation and targeting capabilities to launch personalized
            cross-sell and up-sell campaigns across Internet and traditional
            channels

      (iv)  relationship marketing programs that automate personalized
            communication with prospects

      (v)   Web behavior analysis for: customer profiling and segmentation;
            up-sell and cross-sell offer recommendations, medium selection,
            merchandising and content, effectiveness and site personalization.

                  (d) SAVINGS CLAUSE. The Employee agrees that the scope and
terms of this Section 8 are reasonable and that it is the Employee's intent and
desire that this Section 8 be enforced to the fullest extent permissible under
the laws and public policies applied in the jurisdiction in which enforcement is
sought. If any particular provision of this Section 8 is adjudicated to be
invalid or unenforceable, the parties specifically authorize the tribunal making
such determination to edit the invalid or unenforceable provision to allow this
Section 8 to be valid and enforceable to the fullest extent allowed by law or
public policy.

            9. SUCCESSORS.


                                       5
<PAGE>   6
                  (a) COMPANY'S SUCCESSORS. This Agreement shall be binding upon
any successor (whether direct or indirect and whether by purchase, lease,
merger, consolidation, liquidation or otherwise) to all or substantially all of
the Company's business and/or assets. For all purposes under this Agreement, the
term "Company" shall include any successor to the Company's business and/or
assets which becomes bound by this Agreement.

                  (b) EMPLOYEE'S SUCCESSORS. This Agreement and all rights of
the Employee hereunder shall inure to the benefit of, and be enforceable by, the
Employee's personal or legal representatives, executors, administrators,
successors, heirs, distributees, devisees and legatees.

            10. MISCELLANEOUS PROVISIONS.

                  (a) NOTICE. Notices and all other communications contemplated
by this Agreement shall be in writing and shall be deemed to have been duly
given when personally delivered or when mailed by U.S. registered or certified
mail, return receipt requested and postage prepaid. In the case of the Employee,
mailed notices shall be addressed to him at the home address which he most
recently communicated to the Company in writing. In the case of the Company,
mailed notices shall be addressed to its corporate headquarters, and all notices
shall be directed to the attention of its Secretary.

                  (b) MODIFICATIONS AND WAIVERS. No provision of this Agreement
shall be modified, waived or discharged unless the modification, waiver or
discharge is agreed to in writing and signed by the Employee and by an
authorized officer of the Company (other than the Employee). No waiver by either
party of any breach of, or of compliance with, any condition or provision of
this Agreement by the other party shall be considered a waiver of any other
condition or provision or of the same condition or provision at another time.

                  (c) WHOLE AGREEMENT. No other agreements, representations or
understandings (whether oral or written and whether express or implied) which
are not expressly set forth in this Agreement have been made or entered into by
either party with respect to the subject matter hereof. This Agreement and the
Proprietary Information and Inventions Agreement contain the entire
understanding of the parties with respect to the subject matter hereof. This
Agreement shall supersede in its entirety the offer letter executed by the
Employee and Rubric and any Restricted Stock Purchase Agreement between the
Employee and Rubric to the extent inconsistent herewith.

                  (d) WITHHOLDING TAXES. All payments made under this Agreement
shall be subject to reduction to reflect taxes or other charges required to be
withheld by law.

                  (e) CHOICE OF LAW AND SEVERABILITY. This Agreement shall be
interpreted in accordance with the laws of the State of California (except their
provisions governing the choice of law). If any provision of this Agreement
becomes or is deemed invalid, illegal or unenforceable in any jurisdiction by
reason of the scope, extent or duration of its coverage, then such provision
shall be deemed amended to the extent necessary to conform to applicable law so
as to be valid and enforceable or, if such provision cannot be so amended
without materially altering the intention of the parties, then such provision
shall be stricken and


                                       6
<PAGE>   7
the remainder of this Agreement shall continue in full force and effect. Should
there ever occur any conflict between any provision contained in this Agreement
and any present or future statute, law, ordinance or regulation contrary to
which the parties have no legal right to contract, then the latter shall prevail
but the provision of this Agreement affected thereby shall be curtailed and
limited only to the extent necessary to bring it into compliance with applicable
law. All the other terms and provisions of this Agreement shall continue in full
force and effect without impairment or limitation.

                  (f) ARBITRATION. Any controversy or claim arising out of or
relating to this Agreement or the breach thereof, or the Employee's Employment
or the termination thereof, with the exception of any controversy or claim
arising out of or relating to Section 8, shall be settled in Palo Alto,
California, by arbitration in accordance with the National Rules for the
Resolution of Employment Disputes of the American Arbitration Association. The
decision of the arbitrator shall be final and binding on the parties, and
judgment on the award rendered by the arbitrator may be entered in any court
having jurisdiction thereof. The parties hereby agree that the arbitrator shall
be empowered to enter an equitable decree mandating specific enforcement of the
terms of this Agreement. The Company and the Employee shall share equally all
fees and expenses of the arbitrator. Any controversy or claim arising out of or
relating to Section 8 shall be settled in the appropriate federal or state court
in the State of California. The Company and the Employee hereby consent to
personal jurisdiction of the state and federal courts located in the State of
California for any action or proceeding arising from or relating to this
Agreement or relating to any arbitration in which the parties are participants.

                  (g) NO ASSIGNMENT. This Agreement and all rights and
obligations of the Employee hereunder are personal to the Employee and may not
be transferred or assigned by the Employee at any time. The Company may assign
its rights under this Agreement to any entity that assumes the Company's
obligations hereunder in connection with any sale or transfer of all or a
substantial portion of the Company's assets to such entity.

                  (h) COUNTERPARTS. This Agreement may be executed in two or
more counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.


            IN WITNESS WHEREOF, each of the parties has executed this Agreement,
in the case of the Company by its duly authorized officer, as of the day and
year first above written.


                                       /s/ ANU SHUKLA
                                       -----------------------------------------
                                       ANU SHUKLA






                                       BROADBASE SOFTWARE, INC.




                                       By      /s/ CHUCK BAY
                                              ----------------------------------
                                       Title:  President
                                              ----------------------------------


                                       7