United States: Cybersecurity Information Sharing Act: Updated Guidance Issued

The Cybersecurity Information Sharing Act of 2015 ("CISA") created new legal authorizations and protections for the sharing of cyber threat indicators and defensive measures between and within the private sector and the federal government. (See our update on the bill's passage.)

CISA required various federal agencies to issue guidance, policies and procedures to support this information sharing. On February 16, 2016, the federal government released four implementation documents:

  • Guidance to Assist Non-Federal Entities to Share Cyber Threat Indicators and Defensive Measures with Federal Entities Under CISA;
  • Privacy and Civil Liberties Interim Guidelines: CISA;
  • Interim Procedures Related to the Receipt of Cyber Threat Indicators and Defensive Measures by the Federal Government; and
  • Sharing of Cyber Threat Indicators and Defensive Measures by the Federal Government Under CISA.

On June 15, 2016, updated versions of the first three documents listed above were released through the website of the Department of Homeland Security's ("DHS") Automated Indicator Sharing capability and announced in the Federal Register. (No update of the fourth document was provided and no further update is required by CISA.) Here, we highlight certain elements of these three updated documents, with a particular focus on where they provide expanded clarifications and explanations. (For a fuller discussion of all four documents, please see our update on the February 2016 guidance.)

"Guidance to Assist Non-Federal Entities to Share Cyber Threat Indicators and Defensive Measures with Federal Entities Under the Cybersecurity Information Sharing Act of 2015"

The "Non-Federal Entity Guidance" continues to address three primary topics: (i) key concepts; (ii) how to share cyber threat indicators and defensive measures with the federal government; and (iii) other protections for sharing entities. The revisions released on June 15, 2016, expand several discussions on those topics and, at the request of "multiple private organizations," add a new discussion of sharing between non-federal entities.

Key Concepts

The updated Non-Federal Entity Guidance reiterates key concepts such as the definitions of a "cyber threat indicator" and a "defensive measure" (for additional detail, please see our prior update) while also offering more detail on the meaning of "Information Protected Under Otherwise Applicable Privacy Laws." For example, the updated guidance confirms that "otherwise conflicting laws, including privacy laws, do not restrict sharing or any other action undertaken pursuant to CISA."

Sharing Information with the Federal Government

The updated Non-Federal Entity Guidance reiterates that CISA "only authorizes information sharing for a cybersecurity purpose" and does not require private entities to share information with the federal government. Within this general framework, the guidance provides further detail on how a private entity should share cyber threat indicators and defensive measures with the federal government in order to benefit from the liability protections provided by CISA. The guidance highlights that, where CISA's other requirements are met (e.g., personal information is removed from cyber threat indicators), information sharing with "the federal government through the DHS capability and process" receives liability protection. It also emphasizes that CISA authorizes additional sharing "with any federal entity, including sector-specific agencies." The guidance confirms, however, that sharing with an entity other than DHS—although authorized—generally will not receive CISA's liability protections "even if a federal entity receiving the information shares it with DHS immediately upon receipt."

The guidance also offers more details on the pathways for sharing information with DHS in order to be eligible for CISA's liability protections. Specifically, the February 2016 guidance explained that sharing with DHS may be conducted through Automated Indicator Sharing; a web form on a DHS National Cybersecurity and Communications Integration Center ("NCCIC") website; email to DHS; and sharing with an Information Sharing and Analysis Organization or Center ("ISAO" or "ISAC"). The updated guidance confirms that entities also may receive CISA's liability protections for sharing with the NCCIC through "other DHS programs," including "programs that leverage automated machine-to-machine sharing, web forms or email." As an example, it highlights DHS's Cybersecurity Information Sharing and Collaboration Program, through which stakeholders "may share cyber threat indicators or defensive measures."

The updated guidance also now highlights "two additional means of liability-protected sharing" with the federal government beyond sharing with DHS; each receives liability protections when CISA's other requirements are met. First, CISA protects "communications between a federal entity and a non-federal entity regarding a previously shared cyber threat indicator to describe the relevant cybersecurity threat or develop a defensive measure." The guidance clarifies that this exception would apply when a non-federal entity first shares information through the DHS capability and then engages in subsequent communications about that information with another federal entity through other channels. Second, CISA states that "communications by a regulated non-federal entity with such entity's federal regulatory authority regarding a cybersecurity threat" are also protected. The guidance notes that this protected sharing "is not expressly limited to communications about a previously shared communication."

Other Protections Received by Sharing Entities

The updated guidance continues to emphasize six protections that attach to sharing pursuant to CISA (including when liability protections do not attach): antitrust exemption; exemption from state and federal disclosure laws; exemption from certain state and federal regulatory uses; no waiver of privilege for shared material; treatment of commercial, financial and proprietary information; and ex parte communications waiver.

Sharing Between Non-Governmental Entities

The updated guidance reports that "multiple private organizations have requested" "guidance covering how private entities may share cyber threat indicators and defensive measures with each other under CISA." Though generally focused on sharing with federal entities, the updated guidance thus provides a new "summary of the protections and exemptions that non-governmental entities receive for sharing cyber threat indicators and defensive measures with each other in accordance with CISA." For example, it clarifies that CISA authorizes and provides liability protections to private entities that share cyber threat indicators and defensive measures with other private entities in accordance with the statute. The guidance then reiterates that "under CISA only cyber threat indicators and defensive measures may be shared, and the removal of certain personal information ... is required."

"Privacy and Civil Liberties Final Guidelines: Cybersecurity Information Sharing Act of 2015"

The "Privacy Guidelines" govern "the receipt, retention, use, and dissemination of cyber threat indicators by a federal entity obtained in connection with activities authorized in CISA." They discuss federal requirements related to the receipt of information by the federal government; notifications to federal entities when a cyber threat indicator or defensive measure has been shared in error or in contravention of CISA; notifications to United States persons whose information is shared in violation of CISA; and the use, safeguarding, retention and dissemination of information shared pursuant to CISA. They also discuss appropriate sanctions for violations of CISA by government employees and audit mechanisms established to ensure compliance.

The final version of the Privacy Guidelines further elaborates on these points. For example, the final Privacy Guidelines clarify that if a federal entity determines that it has shared personal information of a United States person in violation of CISA, it should distribute a revised cyber threat indicator or defensive measure that excises that information. The final Privacy Guidelines also note, for example, that other federal entities must "promptly apply the update to replace and delete, to the maximum extent practicable, the information pertaining to a United States person that was shared in violation of CISA."

"Final Procedures Related to the Receipt of Cyber Threat Indicators and Defensive Measures by the Federal Government"

The "Receipt Procedures" describe the federal government's "processes for receiving, handling, and disseminating information that is shared with DHS pursuant to section 104(c) of CISA, including through operation of the DHS Automated Indicator Sharing capability." The final Receipt Procedures primarily serve to clarify the original guidance, expanding on a few key points.

One change concerns anonymous submission of cyber threat information to DHS. The original Receipt Procedures stated that even anonymous submitters had to "identify the sector to which they belong as well as their approximate geolocation (e.g., city and state)." Even if the submitter had not consented to distribution of his or her information outside of DHS, those basic details would be shared "in all instances." The final Receipt Procedures provide for potentially greater anonymity by requiring entities to disclose their sector and "country and state/region" in order to share privately with DHS.


With completion of the updated guidance discussed above, the federal government's attention is likely now to shift to encouraging expanded information sharing pursuant to CISA. The implementation documents will serve as important references going forward as companies assess opportunities and risks associated with such information sharing. In particular, they confirm that companies should carefully consider whether contemplated or ongoing information sharing both is authorized by the statute and benefits from the liability protections CISA provides.


*The firm wishes to thank Alexander Loomis, a summer associate in the firm's Washington DC office, who contributed to the drafting of this legal update.

Originally published on 28 June 2016

Learn more about our Cybersecurity & Data Privacy practice.

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This Mayer Brown article provides information and comments on legal issues and developments of interest. The foregoing is not a comprehensive treatment of the subject matter covered and is not intended to provide legal advice. Readers should seek specific legal advice before taking any action with respect to the matters discussed herein.

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