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                                                                  EXHIBIT 10.12


                                [ISS Letterhead]




December 10, 1999


Mr. Mark Hangen
24432 Pressonville Road
Wellsville, KS  66092

Dear Mark:

I am pleased to make this offer for you to join our team at Internet Security
Systems. As Chief Operations Officer, your total compensation package will be
$450,000 annually at plan. The annual compensation will consist of a base
salary of $300,000 annually ($12,500 paid semi-monthly salary) plus a bonus
paid quarterly at plan in the amount of $20,000. The actual bonus paid will be
a function of company performance and individual objectives, as defined in the
attached performance compensation plan. In addition, you will be eligible for a
$70,000 annual bonus based solely upon ISS achievements of its 2000 sales and
performance objectives. Additionally, you will be granted an option to purchase
300,000 shares of ISS Common Stock, contingent upon the approval by the ISS
Board of Directors, at an exercise price equal to the closing price of ISS
common stock at the date of the grant by the Board of Directors at or after
your date of employment. These options will have our standard four-year annual
vesting schedule. In addition, you will be granted an additional 100,000 shares
of ISS common stock at the same time which vests according to the attached
schedule. These options shall be subject to all of the terms and conditions set
forth in ISS' Amended and Restated 1995 Stock Option Plan.

Additionally, if ISS terminates your employment without cause, ISS will
accelerate the vesting of your 300,000 share grant of options to the same
extent as if you had remained employed by ISS for one (1) year following the
date of the termination. ISS will not accelerate vesting if your resign from
your employment with ISS or if your employment with ISS is terminated for
Cause. As used herein, "Cause" means a termination based on (i) your conviction
of a felony or any other offense evidencing fraud or moral turpitude, (ii) your
failure or refusal to follow the lawful and proper directives of the Company
which is not corrected within seven (7) days after your receipt of written
notice identifying such failure or refusal, (iii) your willful malfeasance or
gross misconduct which discredits or damages the Company, (iv) any breach of
your obligations to maintain the confidentiality of ISS' confidential any
proprietary information and trade secrets, or (v) your chronic absence from
work.


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Your job responsibilities shall be as outlined in the attached job position
responsibilities. ISS agrees to provide for your health benefits in accordance
with the current ISS Benefits plan. ISS will provide for three weeks of paid
vacation/sick leave during your first year of employment as defined in company
benefits program. In addition, you will be eligible to participate in the ISS
401 K program, the ISS Employee Stock Purchase Program (ESPP), and the ISS
Flexible Benefits Program (FLEX).

As I explained to you, this offer of employment is conditional upon the
following:

1)       Your execution of the standard form ISS intellectual property
         Agreement which obligates you to protect ISS proprietary and
         confidential information and in addition, obligates you to refrain
         from using any confidential information from previous employers.

2)       Your providing proof of personal identity and employability. In
         connection with this contingency, please complete the top of the
         enclosed I-9 form. Bring this I-9 form, and substantiating documents
         as outlined on the form to provide personal identity and employment
         eligibility, to my office on your first day of work.

3)       ISS satisfactory review of personal and professional references and
         satisfactory results of the ISS background investigation that will
         require your completion of an application and authorization form
         allowing such investigation. This process is, by our policy, a
         condition of employment by ISS. This process can be coordinated
         through our Director of Human Resources, Terri Jones.

ISS is an at-will employer, which means that employment with ISS is for no
specific period of time and either your or ISS are free to terminate your
employment relationship at any time for any reason, with or without cause. This
is the full and complete agreement between us on this term and supercedes any
prior representations or agreements, whether oral or written. Although your job
duties, title, compensation and benefits, as well as ISS personnel policies and
procedures, may change form time-to-time, the "at-will" nature of your
employment may only be changed in a document signed by you and the President or
the Vice President of Finance and Administration of the Company.

Based upon your acceptance of this offer, we would like for you to join us on
or before December 20, 1999.


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Mark, I look forward to having you join the ISS team and to building a dynamic,
successful enterprise with you. Please do not hesitate to contact me at (w)
678-443-6450 or (h) 770-541-0021 to discuss this offer or any additional
questions or concerns. Again, I am excited to extend this offer of employment
and look forward to working with you.


                                         Sincerely,

                                         /s/ Thomas E. Noonan

                                         Thomas E. Noonan
                                         President and CEO


Accepted:


/s/ Mark Hangen
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Mark Hangen

12/14/00
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Date