Best for: C5 is primarily intended for professional cloud service providers, their auditors and customers. Cloud service customers use it as a guide when selecting a provider and as a foundation for their own risk management.
Controls by category
65 controls are Mapped to BSI C5:2025.
AM-01.01AC The information collected about assets is considered in logging and monitoring applications to identify the impact on cloud services and functions in case of events that could lead to a breach of protection objectives, and to support information provided to affected cloud service...
AM-07.02B The decommissioning includes the complete and permanent deletion of all cloud service customer data, cloud service derived data, cloud service provider data and account data or proper destruction of the media. However, account data is only to be deleted if the data is located in the...
AM-09.01B Assets are classified and, if possible, labelled. Classification and labelling of an asset reflect the protection needs of the category of cloud service customer data, cloud service derived data, cloud service provider data and account data it processes, stores, or transmits.
AM-09.03AC Logging and monitoring applications take the asset protection needs into account in order to inform the responsible stakeholder of events that could lead to a violation of the protection goals, so that the necessary measures are taken with an appropriate priority.
AM-12.01AC Policies and instructions for endpoint devices and removable storage media shall furthermore contain the following aspects: - Managed endpoints are configured with appropriate software firewalls;- Managed endpoints are configured with Data Loss Prevention (DLP) technologies and rules...
BCM-01.02B Policies and instructions for establishing the strategy and guidelines to ensure business continuity management for the cloud service are documented, communicated and provided in accordance with SP-01.
BCM-01.05B Policies and instructions related to business impact analyses and business continuity plans are documented, communicated and made available in accordance with SP-01.
COS-02.01B Specific security requirements are designed, published and provided for establishing connections within the cloud service provider's network. The security requirements define for the cloud service provider's area of responsibility: - In which cases the security zones are to be...
COS-03.02B Physical and virtualised network environments are designed and configured to restrict and monitor the established connection to trusted or untrusted networks according to the defined security requirements.
COS-04.01B Each network perimeter is controlled by security gateways. The system access authorisation for cross-network access is based on a security assessment based on the requirements of the cloud service customers.
COS-08.02B Technical measures outlined in the documented policies and instructions to protect the transmission of data are implemented. These measures are regularly verified to maintain their operating effectiveness.
CRY-01.02AC The cloud provider's PQC strategy is aligned with cryptography policies and procedures and includes the following aspects: - Maintenance of an inventory of cryptographic mechanisms in use, including priority levels to each inventory item based on the impact and probabilities of the...
CRY-03.01B The cloud service provider ensures that encryption, authentication and key management practices are regularly audited in accordance with COM-02 to identify and address potential vulnerabilities. At a minimum, reviews are performed annually and immediately following security incidents...
CRY-04.01AS The cloud service provider has established procedures and technical measures for state-of-the-art encryption and authentication for the transmission of all data.
CRY-04.01B The cloud service provider has established procedures and technical measures for state-of-the-art encryption and authentication for the transmission of cloud service customer data and cloud service derived data both to or by the cloud service provider over public networks. The cloud...
CRY-05.01B The cloud service provider has established procedures and technical safeguards to encrypt cloud service customer data during storage (i.e. at rest).
CRY-05.02B The private keys used for encryption are known only to the cloud service customer in accordance with applicable legal and regulatory obligations and requirements. Exceptions follow a specified procedure.
CRY-07.01B The cloud service provider has established a schedule for rotating cryptographic keys that aligns with the requirements for cryptographic key rotation established in CRY-01. If, based on the results of a risk analysis, the cloud service provider does not perform key rotation, this...
CRY-10.01B The cloud service provider has documented and implemented technical measures for the secure storage of cryptographic keys. This includes ensuring separation of the key management system from the application and middleware layers, defining how authorised users gain access and...
CRY-11.01B The cloud service provider has documented and implemented procedures and technical measures for the secure archiving of cryptographic keys. These include: - Storage of archived keys in a secure repository to prevent unauthorised access;- Restriction of access to archived keys to...
CRY-19.01B The cloud service provider implements procedures and technical safeguards to ensure the secure handling of cryptographic keys managed by cloud service customers. In these procedures, the following aspects are considered: - Secure integration of customer-managed keys into the cloud...
DEV-08.02B The configuration of these system components ensures that all changes to system components in the production environment are recorded and can be traced back to the individuals or system components contributing to their development, deployment or implementation.
DEV-11.02B The cloud service provider includes the development environment as part of the backup plan in accordance with the backup concept (cf. OPS-06).
DEV-12.02B Unless unavoidable, the cloud service provider does not reuse the cryptographic secret and private keys and other secrets used in production environments in other, non-production environments. Any unavoidable reuse of the cryptographic secret and private keys between production and...
HR-01.01B The cloud service provider identifies which roles within the organisation can access cloud service customer data, cloud service derived data, cloud service provider data, account data or system components under the cloud service provider's responsibility that provide the cloud service...
IAM-01.01B The cloud service provider documents, communicates and makes available according to SP-01: - A role, rights and authorities concept based on role-based access control and the business and security requirements of the cloud service provider; and- A policy for managing user accounts and...
IAM-03.01AC The cloud service provider monitors the context of authentication attempts, e.g. IP addresses, the date and time or the device used, and flags suspicious events to authorised persons, as relevant.
IAM-06.01B Privileged access rights for internal and external employees as well as technical users of the cloud service provider are assigned and changed in accordance with the policy for managing user accounts and access rights (cf. IAM-01) or a separate specific policy.
IAM-06.02B Privileged access rights are personalised, limited in time according to a risk assessment and assigned as necessary for the execution of tasks ('need-to-know principle').
IAM-06.06B When such an event is identified, the responsible personnel is automatically informed so that they can promptly assess whether misuse has occurred and take corresponding action.
IAM-07.04B Unless contractually agreed otherwise, the information contains the cause, time, duration, geographic location, type and scope of the access, as well as the retention time of other data generated during access, such as logs or copies containing cloud service customer data. The...
IAM-08.02B Authentication credentials are managed with a security level that matches or exceeds the classification of the system component they protect.
IAM-08.05B The cloud service provider documents, communicates and makes available to all users under its responsibility rules and recommendations for the management of credentials, including at least: - Non-reuse of credentials;- Trade-offs between entropy and ability to memorise;-...
IAM-09.03B Within the production environment, user authentication takes place through passwords, digitally signed certificates or procedures that achieve at least an equivalent level of security. If digitally signed certificates are used, administration is carried out in accordance with the...
IAM-10.01B The cloud service provider ensures that access to its internal data and system functions is controlled and restricted to authorised personnel.
IAM-10.02B The cloud service provider establishes processes and technical controls to manage and verify access permissions within its internal systems.
INQ-02.01B The cloud service provider informs the affected cloud service customer(s) without undue delay. Exceptions for this information of the customer need to be justified by the legal basis of this request or because there are clear indications of illegal actions of the customer in...
INQ-04.01AC The cloud service provider monitors the access and activities performed by or on behalf of investigators as determined by the process described in INQ-01.
OIS-04.01B Conflicting tasks and responsibilities are segregated based on a risk assessment in accordance with OIS-07 to reduce the risk of unauthorised or unintended changes or misuse of cloud service customer data, cloud service derived data and cloud service provider data. The risk assessment...
OIS-04.03B If segregation cannot be established for organisational or technical reasons, measures are in place to monitor the activities in order to detect unauthorised or unintended changes as well as misuse and to take appropriate actions.
OIS-05.01B The cloud service provider collects information from selected internal and external sources to gain a comprehensive view of the threat landscape that lead to cybersecurity risks.
OIS-05.03B The threat intelligence insights are included in the risk management process (cf. OIS-07 and OIS-08) to ensure that the current internal and external threats are reflected in risk handling measures.
OIS-08.02B The following aspects are taken into account when identifying risks, insofar as they are applicable to the cloud service provided and are within the area of responsibility of the cloud service provider: - Processing, storage or transmission of cloud service customer data and cloud...
OPS-05.02AC Policies and instructions describe the technical measures taken to securely configure and monitor the management console (both the customer's self-service and the service provider's cloud administration) to protect it from malware.
OPS-05.04AC Deviations from the specifications are automatically reported to the cloud service provider's subject matter experts so that they can be immediately assessed and the necessary measures taken.
OPS-06.01B Policies and instructions for at least daily backup and restore of cloud service customer data, cloud service derived data and cloud service provider data according to the sensitivity of the data are documented, communicated and provided in accordance with SP-01 regarding the...
OPS-07.01B The execution of backups of cloud service customer data, cloud service derived data and cloud service provider data is monitored by technical and organisational measures documented and implemented in accordance with the policies and instructions defined in OPS-06.
OPS-08.01B Restore procedures are tested regularly, at least annually. The tests include cloud service customer data, cloud service derived data and cloud service provider data in accordance with the contractual agreements.
OPS-08.03B Cloud service customer data is only restored in environments that are subject to the same access restrictions as the production environment.
OPS-12.01B The requirements for the logging and monitoring of events and for the secure handling of cloud service derived data and cloud service provider data are implemented by technically supported procedures with regard to the following restrictions: - Access only for authorised users and...
OPS-13.01AC The cloud service provider validates that event detection processes operate as intended on appropriate assets as identified in the asset classification schema (cf. AM-09).
OPS-13.01B The cloud service provider integrates relevant log data (cloud service derived data and cloud service provider data) into a Security Information and Event Management (SIEM) system to establish a seamless connection between logging, monitoring, and security incident management.
OPS-13.02B The SIEM system can be deployed within the cloud environment or externally and shall include the following capabilities: - Standardisation of log data;- Automated analysis to identify and correlate potential security incidents;- Capabilities to detect unusual behaviour and potential...
OPS-15.01AC On request of the cloud service customer, the cloud service provider provides the logs relating to the cloud service customer in an appropriate form and in a timely manner so that the cloud service customer can investigate any incidents relating to them.
OPS-15.01B The log data generated (cloud service derived data and cloud service provider data) allows an unambiguous identification of user accesses at tenant level to support (forensic) analysis in the event of an incident.
OPS-15.02AC Such logs are collected in a way that allows their use as credible evidence. This includes: - Records are complete and have not been tampered with in any way;- Logging systems are clock synchronised, logs include accurate timestamps;- Copies of electronic evidence are provably...
OPS-15.03B The cloud service provider is able to support forensic analysis of incidents and to retain a chain of evidence. This implies that the cloud service provider capture the state of infrastructure components and network communication during security events.
OPS-17.02B Failures are automatically and promptly reported to the cloud service provider's responsible departments so that these can assess the failures and take required action.
OPS-24.01B The cloud service provider periodically informs the cloud service customer on the status of incidents affecting the cloud service customer, or, where appropriate and necessary, involve the customer in the resolution, in a manner consistent with the contractual agreements.
OPS-24.02B As soon as an incident has been resolved from the cloud service provider's perspective, the cloud service customer is informed about the actions taken according to the contractual agreements.
OPS-25.01B System components in the area of responsibility of the cloud service provider for the provision of the cloud service are subject to vulnerability scans at least once a month in accordance with the policies for handling vulnerabilities (cf. OPS-18). These vulnerability scans include a...
OPS-26.01AS System components in the cloud service provider's area of responsibility are automatically monitored for compliance with hardening specifications.
OPS-32.02B The guidelines and instructions should describe measures along the life cycle of containers and address at least the following aspects: - Containers are inventoried according to a documented process (cf. AM-02, AM-03, AM-09);- The need for malware protection is assessed and, if...
PI-01.01AC The cloud service provider sets up an application firewall to protect the administration interfaces for cloud service customers that are accessible over public networks.
PS-03.02B The security measures are designed to detect and prevent unauthorised access so that the information security of the cloud service is not compromised.
PSS-04.01B The cloud service provided is equipped with error handling and logging mechanisms for system components under the responsibility of the cloud service customer. These enable cloud users to obtain security-related information about the security status of the cloud service as well as the...
PSS-04.05B If the cloud service customer is responsible for the activation or type and scope of logging, the cloud service provider has provide appropriate logging capabilities.
PSS-05.01B The cloud service provider provides authentication mechanisms that can force strong authentication (e.g. two or more factors) for users, IT components or applications within the cloud users' area of responsibility. These authentication mechanisms are set up at all access points that...
PSS-09.01AC Access controls are attribute-based to enable granular and contextual checks against multiple attributes of a user, IT component, or application (e.g., role, location, authentication method).
PSS-11.01AC At startup and runtime of virtual machine or container images, an integrity check is performed that detects image manipulations and reports them to the cloud service customer.
PSS-11.01B If cloud service customers operate virtual machines or containers with the cloud service, the cloud service provider ensures the following aspects: - Cloud service customers can restrict the selection of images of virtual machines or containers according to their specifications, so...
SIM-01.02AC In addition, there are analysis plans for typical security incidents and an evaluation methodology which ensures the collected information does not lose its evidential value in any subsequent legal assessment.
SIM-01.03B Communication channels with the cloud service customers are identified and defined and customers affected by security incidents are informed in a timely and appropriate manner.
SIM-03.01B Subject matter experts of the cloud service provider classify, prioritise and perform root-cause analyses for events that could constitute a security incident.
SIM-03.06B All documents and evidence that provide details on security incidents related to the cloud service are archived in a way that could be used as evidence in court. Security mechanisms and processes for protecting all the information about security incidents related to the cloud service...
SSO-05.01AC The procedures for monitoring compliance with the requirements are supplemented by automatic procedures relating to the following aspects: - Configuration of system components;- Performance and availability of system components;- Response time to malfunctions and security incidents;...
The Federal Office for Information Security (BSI) in Germany publishes C5, the Cloud Computing Compliance Criteria Catalogue. It was first published in 2016 and was completely revised in 2025/26.
What does C5 specify?
C5 specifies minimum requirements for secure cloud computing. It sets a baseline security level for cloud services and aims to illustrate information security in a transparent way, based on a standardized examination and report.
How is alignment with C5 demonstrated?
A cloud service provider can mandate certified public accountants or other auditors of their choice to conduct an examination. Auditors produce a detailed examination report according to international standards, including a system description of the implemented procedures, processes and measures.
What must cloud service customers do with C5 reports?
Customers should order the C5 report from the cloud service provider, analyse it, and repeat this yearly as part of their own risk assessment. BSI does not select auditors or check audit reports, so customers draw their own conclusions and decide whether the baseline is sufficient.
