ISACA Journal
Volume 2, 2,017 


Navigating the US Federal Government Agency ATO Process for IT Security Professionals 

Jo Anna Bennerson, CISA, CGEIT, CPA, ITILv3, PMP 

IT security professionals such as risk managers and information security managers maintain a US federal government agency’s information system using the Federal Information Security Management Act (FISMA) in a manner that is unique to the US federal government. To do so, they encounter the Authority to Operate (ATO) security authorization process, which is in place for the security of the agency’s information systems.

The ATO is the authority to operate decision that culminates from the security authorization process of an information technology system in the US federal government, which is a unique industry requiring specialized practices. Figure 1 provides information about an ATO.

This article discusses approaches to increase an information security professional’s knowledge about the US federal government ATO security authorization process and one’s duties in the narrow US federal government industry.

The ATO security process is in place for the federal government agency to determine whether to grant a particular information system authorization to operate for a certain period of time by evaluating if the risk of security controls can be accepted. The ATO process:

  • Is not an audit, nor is it to be termed an ATO audit
  • Documents the security measures taken and the security process in place for US federal government agencies by focusing on a specific system
  • Produces documentation that can sometimes be used as evidence in another assessment such as an internal audit, for example, by sharing copies of change management requests that can be used. Shared documentation often can be used as part of an integrated assurance process.
  • Often engages professionals across many areas of different federal agencies to cover security and privacy controls. No qualifications are spelled out for those engaged in the ATO process. For example, someone from the budget department may be asked about acquisition documents, a system administrator may be asked to provide a procedure about access provisioning, or a project manager may be requested to present a project plan that highlights the timeline for corrective actions to be implemented in the system.
  • Has no current skill gap and does not denote the need for particular global certifications. However, Certified Information Systems Auditor (CISA), Certified in Risk and Information Systems Control (CRISC), Certified Information Security Manager (CISM), Certified in the Governance of Enterprise IT (CGEIT) or other IT professional certification and experience will likely more rapidly engage one in the ATO process.

ATO Process Steps and Knowing the IT Governance Frameworks

To understand the ATO process, one needs to understand the IT governance frameworks. The required steps for conducting the ATO security authorization process are:

  1. Categorize the information systems in the organization, i.e., determine the criticality of the information system based on potential adverse impact to the business.
  2. Select baseline security controls.
  3. Implement these security controls, i.e., implement security controls within the agency’s enterprise architecture.
  4. Assess the security controls to determine their effectiveness.
  5. Authorize the system.
  6. Monitor the system.

The information security professional works to gather the documentation for the system project deliverables from the phases (planning, requirements, design, development, testing, implementation and maintenance) of the Software Development Life Cycle (SDLC)8 or System Engineering Life Cycle (SELC)9 frameworks. This information is needed as documentation in the ATO process and shows evidence of the categorize, select, implement and assess steps while simultaneously fulfilling the stated IT governance frameworks.

Figure 2 is a brief overview of US federal government IT security governance.

View Large Graphic.

The key staff in the ATO process with whom one should quickly become acquainted are the authorizing official (AO), the information systems security officer (ISSO) and the security assessor.10 Often, the chief information security officer (CISO) and/or privacy officer serve as the authorizing official. This person is referred to as the senior agency information security official (SAISO) who is the point of contact within a federal government agency and is responsible for its information system security.11

View Large Graphic.

The ISSO works with the system owner serving as a principal advisor on all matters involving the security of the IT system. The ISSO has the detailed knowledge and expertise required to manage its security aspects.

The security assessor conducts a comprehensive assessment of the management, operational and technical security controls, and control enhancements employed within or inherited by an information system to determine the overall effectiveness of the controls (i.e., the extent to which the controls are implemented correctly, operating as intended and producing the desired outcome with respect to meeting its security requirements).

Generally, the ISSO works with the IT team to prepare the required documents—system security plan (SSP), privacy threshold analysis (PTA), contingency plan (CP), etc. Then, the security assessor evaluates the information and prepares a security assessment report (SAR). When all is completed, the AO grants the ATO. Often, auditors can leverage this information for their audits.

Securing With CIA

The overall objective of an information security program is to protect the information and systems that support the operations and assets of the agency via the security objectives shown in figure 3:

  • Confidentiality—Preserving authorized restrictions on information access and disclosure
  • Integrity—Guarding against unauthorized information modification or destruction
  • Availability—Ensuring timely and reliable access to and use of information

Comprehending the NIST Risk Management Framework (RMF)17 sets the foundation for understanding how the security life cycle of the IT system is being operated and evaluated. From the agency’s inventory of its IT systems, the agency will use its own criteria to determine what may be a system that could be part of a FISMA audit, hence a FISMA reportable system. These tend to be the financial reporting systems, general support systems (GSS) and major applications (MA). To accomplish an ATO security authorization, there are six steps in the RMF to be completed (figure 4):

  1. Categorize—What is the system’s overall risk level, based on the security objectives of confidentiality, integrity and availability? Has it been categorized as high, moderate or low impact? Is it a GSS, MA, minor application or subsystem? Delineating and documenting the system boundary is key.18
  2. Select—Using the system’s categorization, have the appropriate level of controls been chosen? Systems will be assessed at the operating system, application and database layers. What controls are being selected to mitigate risk? Baseline security controls of the safeguards or countermeasures employed and specifying minimum assurance requirements are in this step.
  3. Implement—Are the individual controls implemented or planned, or are there compensating controls in place? Are the controls inherited from another system or from common controls, or are they system specific or hybrid? What can demonstrate the controls?
  4. Assess—Through verification of evidence, the controls are tested to determine if they are in place and operating as intended.
  5. Authorize—Documents are submitted to the AO, who will either accept or deny the system’s risk in an accreditation decision. An accreditation package consists of:19
    • Accreditation decision letter
    • System security plan (SSP)—Criteria provided on when the plan should be updated
    • Security assessment report (SAR)—Updated on an ongoing basis for changes made to either the security controls in this information system or to inherited common controls
    • Plan of action and milestones (POAMs) for any remaining remediation of outstanding issues or deficiencies
  6. Monitor—NIST states that the objective of a continuous monitoring program is to determine if the complete set of planned, required and deployed security controls within an information system or inherited by the system continue to be effective over time in light of the inevitable changes that occur. POAMs address changes to the system;20 NIST SP, 800-137 provides guidance (figure 5).21

Security Controls

Figure 6 shows the NIST RMF steps for ATO. There are three classes of security controls: management, operational and technical (MOT). These controls are divided into 18 control families. Figure 7 shows security control families and MOT controls.

View Large Graphic.

Engaging With the ATO Process

The assess step involves answering the following questions:

  • Is the system a GSS or MA or minor application or subsystem?
  • Learning its history, the roles and responsibilities, current state, its system boundaries and which controls are in place or planned?
  • Who executes the controls and where to get evidence such as IP and user access lists (ACLs)?
  • Who provisions access, when are scans run and how are incident reports handled?
  • Who is the contact?
  • What is the evidence of other IT controls (including written documentation, i.e., policies, standard operating procedures [SOPs], service level agreements [SLAs], delegations of authority, common controls, URLs, screen shots)?
  • What is the level of privacy, including PII?

One should request or set a significant lead time to start collecting information for a preliminary or draft of what is historically termed an auditor’s request, the Provided by Client (PBC) list, of schedules, documents, questions, requested spreadsheets, or read-only access to certain repositories or systems.

In summary, one should make full use of NIST 800-53, Revision 4, “Security and Privacy Controls for Federal Information Systems and Organizations,” which emphasizes security and privacy controls.34 Then, use NIST 800-53A, “Assessing Security and Privacy Controls in Federal Information Systems and Organizations: Building Effective Assessment Plans,” to assess the controls.35 In the federal government, there is usually:

  • The ISSO or ISSO team
  • A separate independent assessment team (security assessors) that reviews what the ISSO team has done

These two teams get everything ready for the authorization package in the C&A or A&A security authorization process.

The authorizing official reviews the package to make an ATO decision to grant or deny authorization of the system to operate for three years. If there is significant change to the system, it will need to be reauthorized.36 Remember continuous monitoring and think POAMs.


As an information security professional, one can quickly navigate the US federal government’s industry-specific practices by understanding its ATO process. Using traditional IT security knowledge and becoming familiar with the IT governance of the US federal government, one can understand the process that results in an ATO decision. This is the decision that the information security professional’s federal agency AO makes to accept the risk of the IT system. The ISSO and security assessor teams have documentation that has been developed through the agency’s C&A or A&A security process.

When undertaking work from a FISMA perspective, one should also learn more about the NIST RMF and how controls are planned and implemented to mitigate risk through use of NIST guidance—FIPS 199, FIPS 200, SP 800-53 Rev.4 and SP 800- 53A. This knowledge will not only build a sturdy introductory foundation, but will also serve as the baseline protocol for federal government IT security guidance.


1 Executive Office of the President of the United States, Office of Management and Budget, “M-03-22, OMB Guidance for Implementing the Privacy Provisions of the E-Government Act of 2002,” 26 September 2003
2 The National Partnership for Reinventing Government, Archive, “Summary: Information Technology Management Reform Act of 1996,”
3 National Institute of Standards and Technology, Federal Information Security Management Act of 2002, “Detailed Overview,” USA, 25 August 2016,
4 Ibid.
5 Executive Office of the President of the United States, Office of Management and Budget, “Circular No. A-130 Revised,” 28 November 2000
6 Op cit, National Institute of Standards and Technology, 25 August 2016
7 National Institute of Standards and Technology, “NIST Special Publications (SP),” USA, 8 April 2016,
8 ComputerWorld, “System Development Life Cycle,” 14 May 2001,
9 Department of Homeland Security, Office of Inspector General, “CBP Information Technology Management Strengths and Challenges,” USA, June 2012, fig. 4, p. 12,
10 National Institute of Standards and Technology, “Guide for Applying the Risk Management Framework to Federal Information Systems: A Security Life Cycle Approach, Revision 1,” NIST SP 800-37, USA, February 2010, Appendix D,
11 Department of Homeland Security, ”DHS Sensitive Systems Policy, Directive 4300A, Version 11.0,” USA, 14 January 2015,
12 Department of Homeland Security, “Federal Information Security Modernization Act (FISMA),” USA, 3 October 2016,
13 Ibid.
14 Department of Homeland Security, United States Computer Emergency Readiness Team, “About Us,” USA,
15 Department of Defense, Personnel and Readiness Information Management, “Department of Defense Information Assurance Certification and Accreditation Process (DIACAP),” USA
16 General Services Administration, “FedRAMP Federal Risk and Authorization Management Program,” USA,
17 Op cit, National Institute of Standards and Technology, February 2010
18 Op cit, Department of Homeland Security, 14 January 2015
19 Ibid.
20 National Institute of Standards and Technology, “Frequently Asked Questions, Continuous Monitoring,” USA,
21 National Institute of Standards and Technology, “Information Security Continuous Monitoring (ISCM) for Federal Information Systems and Organizations,” NIST SP 800-137, USA, September 2011,
22 Op cit, National Institute of Standards and Technology, 8 April 2016
23 National Institute of Standards and Technology, “FIPS Publications,” USA, 16 October 2015,
24 Op cit, National Institute of Standards and Technology, February 2010
25 National Institute of Standards and Technology, “Standards for Security Categorization of Federal Information and Information Systems,” FIPS Publication 199, USA, February 2004,
26 National Institute of Standards and Technology, “Volume I: Guide for Mapping Types of Information and Information Systems to Security Categories,” SP 800-60 vol. I, Rev. 1, USA, August 2008,
27 National Institute of Standards and Technology, “Volume II: Appendices to Guide for Mapping Types of Information and Information Systems to Security Categories,” SP 800-60 vol. II, Rev. 1, USA, August 2008,
28 National Institute of Standards and Technology, “Standards for Security Categorization of Federal Information and Information Systems,” FIPS Publication 199, USA, March 2006
29 National Institute of Standards and Technology, “Security and Privacy Controls for Federal Information Systems and Organizations,” NIST SP 800-53 Revision 4, USA, April 2013,
30 National Institute of Standards and Technology, “Assessing Security and Privacy Controls in Federal Information Systems and Organizations,” NIST SP 800-53A Revision 4, USA, December 2014,
31 Op cit, National Institute of Standards and Technology, February 2010
32 National Institute of Standards and Technology, “Supplemental Guidance on Ongoing Authorization: Transitioning to Near Real-Time Risk Management,” USA, June 2014,
33 Op cit, National Institute of Standards and Technology, September 2011
34 Op cit, National Institute of Standards and Technology, April 2013
35 Op cit, National Institute of Standards and Technology, December 2014
36 Department of Homeland Security, “DHS Security Authorization Guide, Version 11.1,” USA, March 2015,

Jo Anna Bennerson, CISA, CGEIT, CPA, ITILv3, PMP
Has more than 20 years of experience as a consultant in the role of information systems security officer for US federal government agencies, having launched her career as a certified public accountant and project manager working in the financial services industry. She has served as a Malcom Baldrige National Quality Award examiner. Bennerson can be reached at


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