United States: The Cybersecurity Information Sharing Act of 2015: An Overview

On December 18, 2015, President Barack Obama signed into law the Cybersecurity Information Sharing Act of 2015 (CISA), which establishes a voluntary system for sharing cyber threat indicators1 and defensive measures2 for a cybersecurity purpose3 between federal entities4 and nonfederal entities.5 Examples of cyber threat indicators include web server logs showing that a particular IP address is testing a company's vulnerabilities on its website; techniques that permit unauthorized access to a control system; malware found on the company's network; domain names or IP addresses associated with botnet command and control servers; discovered vulnerabilities; and IP addresses sending malicious traffic in connection with a distributed denial of service attack. Examples of defensive measures include information about security devices that protects a company's network, such as the configuration of a firewall mechanism, and techniques to protect against phishing campaigns.

CISA provides a safe harbor from civil, regulatory and antitrust liability for nonfederal entities that share this information in accordance with its provisions. However, CISA's safe harbor protection does not shield nonfederal entities from potential liability for data breaches or other cybersecurity incidents. It only shields nonfederal entities from liability for their act of sharing or receiving such information.

CISA only extends civil liability protection for sharing cyber threat indicators and defensive measures to private entities,6 but only if the sharing was done in accordance with CISA (i.e., through DHS-certified channels and mechanisms). Where this sharing is done in a manner not consistent with CISA, private entities do not receive liability protection, but are still eligible for the following CISA protections and exemptions:

  1. federal antitrust exemptions;
  2. exemptions from federal and state disclosure laws, such as federal, state, tribal or local government freedom of information laws, open government laws, open records laws or sunshine laws;
  3. exemptions from certain state and federal regulatory uses, which prevent any federal, state, tribal or local government from bringing an enforcement action based on the sharing, but not the development or implementation of a regulation;
  4. no waiver of any applicable protection or privilege for shared material;
  5. treatment of shared material as commercial, financial and proprietary information when so designated by the sharing entity; and
  6. ex parte communications waiver, which prevents the sharing of cyber threat indicators and defensive measures with the federal government under CISA from being subject to the rules of any federal agency or department or judicial doctrine regarding communications with a decision-making official.7

CISA limits the government's use of the information shared under its provisions and the type of data to which the government has access. The government may only use the information provided under CISA for either a cybersecurity purpose; to identify cybersecurity threats or security vulnerabilities; to respond to, prevent or mitigate a specific threat of death or serious bodily and economic harm; or to investigate or prosecute specific criminal offenses. It may not use the information to bring an enforcement action.

In addition, CISA requires nonfederal entities that share cyber threat indicators and defensive measures to remove all information that the sharing entity "knows at the time of sharing" to be the personal information of a specific individual or information that identifies a specific individual unrelated to the cybersecurity threat.8 The guidance provides a spear-phishing email as an illustration of what should be done. The personal information of the sender of the spear-fishing email, such as the name, email address and content of the email, should be shared, but the personal information of the intended victims should not.

CISA centralizes cybersecurity information sharing between federal entities and nonfederal entities in the Department of Homeland Security (DHS), specifically the National Cybersecurity and Communications Integration Center (NCCIC). On February 16, 2016, the DHS published interim guidance and policies for implementing CISA. On June 15, 2016, the DHS and Department of Justice (DOJ) released the final guidance on implementing CISA.

The final guidance for CISA contemplates the utilization of the Automated Indicator Sharing (AIS) initiative as the primary means of sharing information. The AIS initiative is an automated system that receives, processes and disseminates cyber threat indicators and defensive measures in real time with all AIS participants. The system works by having AIS participants connect to a DHS-managed system in NCCIC. A server housed at each AIS participant's location enables participants to exchange information with the NCCIC. Once the NCCIC has reviewed a submission to determine that there is no personally identifiable information (pii), the indicators and defensive measures will be shared with all AIS participants.

In addition to pii, DHS has identified the types of personal information that are protected by federal and state laws and unlikely to be related to a cybersecurity threat. AIS participants should be particularly diligent about removing the following types of information from their CISA submissions:

  1. protected health information (phi), such as medical records, laboratory reports or hospital bills;
  2. human resource information within an employee's personnel file, such as hiring decisions, performance reviews and disciplinary actions;
  3. consumer information/history related to an individual's purchases, preferences, complaints or credit;
  4. education history, such as transcripts, or training;
  5. financial information, such as bank statements, loan information or credit reports;
  6. identifying information about property ownership, such as property purchase records or vehicle identification numbers; and
  7. identifying information about children under the age of 13 subject to the Children's Online Privacy Protection Act.

After agreeing to the AIS's Terms of Use, AIS participants may submit cyber threat indicators or defensive measures through one of three methods: (1) the DHS Trusted Automated eXchange of Indicator of Information (TAXII) server in the AIS Profile format; (2) a web form on the US-CERT web portal; or (3) by email to DHS.

Participants who share indicators and defensive measures through the AIS will not be identified as the source of that information unless they affirmatively consent to the disclosure of their identities. DHS will not verify the accuracy of the indicators or defensive measures submitted by participants. The AIS Terms of Use require participants to use "reasonable efforts" to ensure that any indicator or defensive measure is accurate at the time that it is submitted.9 However, as the government obtains useful information concerning an indicator or defensive measure, it may assign a reputational score.

Nonfederal entities may continue to provide cyber threat indicators and defensive measures to federal entities through Information Sharing and Analysis Centers (ISACs) and Information Sharing and Analysis Organizations (ISAOs), which are private entities that share cybersecurity information with federal entities through DHS. Private entities that share this information with ISACs and ISOCs in accordance with CISA still receive all the protections and exemptions under CISA. Similarly, ISACs and ISAOs that share information with other private entities in accordance with CISA also receive the same level of protection under CISA.

The implementation of CISA is still a work in progress. It remains to be seen how this information sharing will look and how effective it will be. If they are considering participating, companies should take appropriate steps to ensure the sharing is done in a manner that is consistent with CISA's provisions and maximizes CISA's protections.


1. CISA defines "cyber threat indicator" as:

[I]nformation that is necessary to describe or identify:

(i) malicious reconnaissance, including anomalous patterns of communications that appear to be transmitted for the purpose of gathering technical information related to a cybersecurity threat or security vulnerability;

(ii) a method of defeating a security control or exploitation of a security vulnerability;

(iii) a security vulnerability, including anomalous activity that appears to indicate the existence of a security vulnerability;

(iv) a method of causing a user with legitimate access to an information system or information that is stored on, processed by or transiting an information system to unwittingly enable the defeat of a security control or exploitation of a security vulnerability;

(v) a malicious cyber command or control;

(vi) the actual or potential harm caused by an incident, including a description of the information exfiltrated as a result of a particular cybersecurity threat;

(vii) any other attribute of a cybersecurity threat, if disclosure of such attribute is not otherwise prohibited by law; or

(viii) any combination of (i)-(vii).

Section 102(6) of CISA.

2. CISA defines "defensive measures" as:

An action, device, procedure, signature, technique or other measure applied to an information system or information that is stored on, processed by or transiting an information system that detects, prevents or mitigates a known or suspected cybersecurity threat or security vulnerability; but does not include a measure that destroys, renders unusable, provides unauthorized access to or substantially harms an information system or information stored on, processed by or transiting such information system not owned by (i) the private entity operating the measure, or (ii) another entity that is unauthorized to provide consent and has provided consent to that private entity for operation of such measure.

Section 102(7) of CISA.

3. CISA defines a "cybersecurity purpose" as "the purpose of protecting an information system or information that is stored on, processed by or transmitting an information system from a cybersecurity threat or security vulnerability." Section 102(4) of CISA.

4. CISA defines a "federal entity" as "a department or agency of the United Sates or any component of such department or agency." Section 102(9).

5. CISA defines a "nonfederal entity" as "any private entity, nonfederal government agency or department, or state, tribal or local government (including a political subdivision, department or component thereof)." Section 102(14) of CISA.

6. CISA defines "private entities" as including "any person or private group, organization, proprietorship, partnership, trust, cooperative, corporation or other commercial or nonprofit entity, including an officer, employee or agent thereof," and "State, tribal or local government performing utility services, such as electric, natural gas or water services." Section 102(15)(A)-(B) of CISA.

7. All of CISA's protections, including liability protection, are available to private entities. However, other state, tribal or local government entities that are not included in CISA's definition of "private entities" are not eligible for liability or antitrust protection, which is reserved for "private entities." These other entities are still eligible for CISA's other protections and exemptions.

8. In addition, CISA enables private entities to monitor and adopt defensive measures for their own information systems for cybersecurity purposes. CISA explicitly shields private entities from any liability for monitoring activities conducted in a manner consistent with its requirements.

9. See U.S. Dep't of Homeland Sec. Terms of Use, § 3.2.

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