ICO (UK) - ACRO Criminal Records Office: Difference between revisions
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Revision as of 12:09, 21 August 2026
| ICO - ACRO Criminal Records Office | |
|---|---|
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| Authority: | ICO (UK) |
| Jurisdiction: | United Kingdom |
| Relevant Law: | Article 32(1) UK GDPR Article 32(1)(b) UK GDPR Article 32(1)(d) UK GDPR |
| Type: | Investigation |
| Outcome: | Violation Found |
| Started: | |
| Decided: | 07.08.2026 |
| Published: | |
| Fine: | n/a |
| Parties: | ACRO Criminal Records Office |
| National Case Number/Name: | ACRO Criminal Records Office |
| European Case Law Identifier: | n/a |
| Appeal: | Unknown |
| Original Language(s): | English |
| Original Source: | ICO (in EN) |
| Initial Contributor: | bms |
The ICO reprimanded ACRO for failing to implement appropriate security measures, including effective patch management and security monitoring, resulting in prolonged unauthorised access to systems containing sensitive personal data.
English Summary
Facts
ACRO Criminal Records Office, the processor, is a national police unit providing public services including Police Certificates, International Child Protection Certificates, Subject Access Requests and Record Deletion Requests. It processes personal data on behalf of 43 police forces whose Chief Constables act as joint controllers.
Between July 2021 and June 2023, three separate security incidents affected the processor's customer portal and its Kentico content management system. The most significant incident occurred between August 2022 and March 2023, during which a threat actor maintained unauthorised access to the processor's website and CMS environment.
In February 2023, the threat actor staged personal data for possible exfiltration relating to Police Certificate applications, Subject Access Requests and International Child Protection Certificate forms. Due to insufficient logging, the processor could not determine whether the data had actually been exfiltrated.
A maximum of 10,920 data subjects were potentially affected. The information concerned included identification and contact data, financial information, identification numbers, criminal conviction and offence data, information concerning domestic violence, disability, gender reassignment and sexual orientation, biometric data, and racial or ethnic origin.
In April 2023, the processor notified 84,048 data subjects on a precautionary basis. Several data subjects subsequently complained about distress and concerns regarding identity theft and financial loss.
Holding
The DPA held that the processor infringed Articles 32(1), 32(1)(b) and 32(1)(d) UK GDPR.
Regarding Article 32(1) UK GDPR, the DPA found that the processor had failed to implement appropriate organisational measures to ensure a level of security appropriate to the risk. In particular, responsibility for identifying required security patches was not clearly allocated and the processor did not itself monitor whether security patches were required.
The DPA further found a violation of Article 32(1)(b) UK GDPR. The processor had operated an outdated version of the Kentico CMS between 2019 and 2023 despite the availability of multiple security hotfixes. It could not demonstrate that known vulnerabilities had been subject to documented risk assessments or formal governance processes and had no documented patching policy. In addition, multiple antivirus alerts indicating malicious activity were neither reviewed nor acted upon, allowing the threat actor to remain undetected.
Finally, the DPA held that the processor infringed Article 32(1)(d) UK GDPR because it lacked effective processes for regularly testing and evaluating its security measures. The absence of a documented patching policy, continuous security monitoring and clearly assigned responsibility for reviewing security alerts prevented the processor from assessing whether its technical and organisational measures remained effective.
Taking into account the seriousness and duration of the infringements, as well as mitigating factors and the remedial measures subsequently implemented by the processor, the DPA issued a reprimand.
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English Machine Translation of the Decision
The decision below is a machine translation of the English original. Please refer to the English original for more details.
UK GENERAL DATA PROTECTION REGULATION
(Article 58(2)(b))
CORRECTIVE POWERS OF THE INFORMATION COMMISSIONER
REPRIMAND
DATED: 7 August 2026
To: ACRO Criminal Records Office
Of: ACRO Criminal Records Office, ACRO, PO Box 481, Fareham,
Hampshire, PO14 9FS
I. INTRODUCTION AND SUMMARY
1. ACRO Criminal Records Office herein referred to as ‘ACRO’ are a
national police unit providing a range of public services such as the
issuing of Police Certificates, International Child Protection
Certificates and the processing of Subject Access Requests
and Record Deletion Requests. ACRO was founded in 2006.
2. ACRO are a data processor for processing activities set out in the
S22A Collaboration Agreement under the Police Act 1996 acting
on behalf of the 43 Police Forces that are party to the agreement.
The Chief Constables party to the agreement are joint controllers.
1
Police Act 1996
2NON-CONFIDENTIAL - FOR PUBLICATION
3. The National Police Chiefs Council (NPCC) is the chair of the ACRO
governance board that governs ACRO’s processing on behalf of the
joint controllers. They fall under the NPCC ICO Registration.
2
4. It is the Information Commissioner’s (the “Commissioner”)
understanding that three separate incidents of compromise
occurred between July 2021 - June 2023, all involving the ACRO
3
customer portal website (www.acro.police.uk), a web application
4
built on the Kentico CMS at the time of the incidents taking place.
5. The Commissioner issues ACRO with this Reprimand pursuant to
Article 58(2)(b) UK General Data Protection Regulation (“UK
GDPR”).
6. The Commissioner finds that between the implementation of the
UK GDPR on 25 May 2018 and 22 June 2023 (the “Relevant
Period”), ACRO infringed Articles 32(1), 32(1)(b), and 32(1)(d) of
the UK GDPR for the reasons set out in this Reprimand.
7. The Commissioner previously served ACRO with a Notice of Intent
to issue a Reprimand (the “NOI”) on 10 June 2026. ACRO provided
written representations (the “Representations”) in response to
the NOI on 1 July 2026. The Commissioner has taken the
Representations into account when deciding to issue this
Reprimand.
2This Notice is issued by Jonathan Balmforth, Group Manager (Civil and Cyber Investigations),
as the delegated authority on behalf of the Information Commissioner in accordance with
paragraph 6(3) of Schedule 12 of the Data Protection Act 2018 and the ICO’s Scheme of
Delegations, (approved July 2025). As stated in Annex 1 of the ICO’s Scheme of Delegations,
the delegation of the Information Commissioner’s non-reserved functions set out in the Scheme
of Delegations continue to apply notwithstanding the vacancy in the office of the Information
Commissioner. The resignation of John Edwards does not affect the continuity or validity of the
process leading to this Notice.
3Interactive platforms that allow users to perform tasks, process data, and engage with
complex functionality through a browser.
4A content management platform primarily used for building and managing websites, online
stores, intranets, and web applications.
3NON-CONFIDENTIAL - FOR PUBLICATION
II. RELEVANT LEGAL FRAMEWORK
8. Article 58(2)(b), the Commissioner has the power “to issue
reprimands to a controller or a processor where processing
operations have infringed provisions of this Regulation”.
9. Article 32(1) states:
“taking into account the state of the art, the costs of
implementation and the nature, scope, context and purposes of
processing as well as the risk of varying likelihood and severity for
the rights and freedoms of natural persons, the controller and the
processor shall implement appropriate technical and organisational
measures to ensure a level of security appropriate to the risk.”
10. Article 32(1)(b) states organisations should:
“ensure the ongoing confidentiality, integrity, availability, and
resilience of processing systems and services”
11. Article 32(1)(d) states organisations should have:
“a process for regularly testing, assessing and evaluating the
effectiveness of technical and organisational measures for ensuring
the security of the processing.”
III. BACKGROUND TO THE INFRINGEMENTS
12. This section summarises the relevant background to the findings of
infringement. It does not seek to provide an exhaustive account of
all the details of the events that have led to the decision to issue
this Reprimand.
Incident Overview
13. In March 2023, the Joint ICT (JICT) department of ACRO’s host
Force, Hampshire and Isle of Wight Constabulary, notified ACRO
4NON-CONFIDENTIAL - FOR PUBLICATION
that there had been an incident raised at the
5
This incident involved an SQL injection attack that
exposed 15 username and password credentials, the majority of
which related to ACRO employees.
14. After notification from the ACRO commissioned
to carry out a forensic
investigation which uncovered three distinct incidents in total, all
involving the ACRO website and its Kentico CMS, with threat actor
activity evidenced between 09 July 2021 - 22 June 2023. Two of
these incidents either did not involve personal data or affected a
small portion of user account credentials, herein these incidents
are referred to as ‘Group B’ and ‘Group C’.
15. The most significant incident, herein referred to as ‘Group A’,
occurred between 5 August 2022 - 14 March 2023, during which
the threat actor maintained unauthorised access to ACRO’s
website/CMS environment. Between 15 - 16 February 2023, the
7
threat actor was able to stage data for exfiltration. The personal
data staged related to Police Certificate Applications, Subject
Access Request (SAR) forms and International Child Protection
Certificate forms. Insufficient logs were retained by ACRO in order
to definitively determine if this data was exfiltrated from their
network.
16. The last evidence of threat actor access to the ACRO website / CMS
environment during the Group A incident was on 14 March 2023.
ACRO took the customer portal section of their website offline on
21 March 2023 in response to the discovery of the Group B
5
A technique used to attack Structured Query Language (SQL) databases by injecting malicious
commands into database queries.
7
Data Staging is the process of extracting data and storing it in a temporary holding place
before complete exfiltration.
5NON-CONFIDENTIAL - FOR PUBLICATION
incident, this limited external access to the compromised systems.
However, the Commissioner considers that the end date for the
Relevant Period should be taken from when the compromised
infrastructure, which continued to be used to process limited
amounts of personal data, was fully decommissioned on 22 June
2023.
17. In total, a maximum of 10,920 data subjects were potentially
affected where their personal data was staged for exfiltration. Not
all data subjects who had personal data staged for exfiltration
would have had personal data falling into every category set out
below:
• Basic Personal Identifiers (first name, surnames, place of birth,
date of birth, proof of address)
• Economic and Financial (account and sort code)
• Identification Numbers (national insurance number, driving
license numbers and passport details)
• Criminal Convictions and Criminal Offences (persons who have
disclosed serious offending, persons who are the perpetrator of
domestic violence)
• Persons who have been subject to domestic violence.
• Disability, Gender Reassignment and Sexual Orientation
information
• Biometric Data
• Race & Ethnic Origin
18. The categories of data subjects potentially affected are applicants,
third parties, nominated parties and, endorsers for Police
Certificates and International Child Protection Certificates. As well
as those requesting Subject Access and Record Deletion.
6NON-CONFIDENTIAL - FOR PUBLICATION
19. In total 84,048 data subjects were notified by ACRO on a
precautionary basis in April 2023. The total of 84,048 data subjects
reflects all individuals who submitted applications between 17
January 2023 - 21 March 2023, plus an additional 18 data subjects
whose applications had been stored for an extended period.
Damage and distress caused to the Data Subjects
20. ACRO received 35 complaints from data subjects potentially
affected, which were evidenced to the Commissioner. The
complaint information provided by ACRO reported distress and
concern arising from the incident, including concerns about the risk
of identity theft and financial loss. Complainants included those
connected to Police Certificates, International Child Protection
Certificates, and victims of domestic violence. ACRO advised that,
in one instance, a
These complaints have not been interrogated by the
Commissioner.
21. The Commissioner separately received a further six complaints.
These complaints report distress and anxiety arising from the
breach, including concerns about identity theft and financial loss.
These complaints have not been interrogated by the
Commissioner.
Mitigating factors
22. During the course of the ICO’s investigation, the Commissioner has
noted that ACRO’s network segmentation measures prevented the
threat actor from moving beyond the compromised environment
into core policing systems, reducing the scale of harm. also
7NON-CONFIDENTIAL - FOR PUBLICATION
confirmed no lateral movement into the wider JICT estate was
observed.
Remedial steps taken by ACRO Criminal Records Office
23. The Commissioner has also considered and welcomes the remedial
steps taken by ACRO in light of this incident. This included
decommissioning the compromised infrastructure, migrating to the
Salesforce Experience Cloud, implementing a SIEM, enhancing
visibilityand monitoring, and introducing stronger system
hardening and network segmentation.
24. The Commissioner recognises that ACRO has made improvements
to its patching arrangements since the incident, including through
its move to Salesforce Experience Cloud, where patching is
governed by Salesforce’s formal change management process and
includes the evaluation and implementation of upgrades, patches
and hotfixes. ACRO has also implemented as its
SIEM solution, improving its ability to detect, analyse and respond
to security threats in real time, and strengthening its response to
security alerts.
IV. THE COMMISSIONER’S FINDINGS OF INFRINGEMENT
25. The Commissioner has decided to issue a reprimand to ACRO
Criminal Records Office in respect of the following infringements of
the UK GDPR:
26. Article 32(1) which states:
“taking into account the state of the art, the costs of
implementation and the nature, scope, context and purposes of
8NON-CONFIDENTIAL - FOR PUBLICATION
processing as well as the risk of varying likelihood and severity for
the rights and freedoms of natural persons, the controller and the
processor shall implement appropriate technical and organisational
measures to ensure a level of security appropriate to the risk.”
27. Article 32(1)(b) which states organisations should:
“ensure the ongoing confidentiality, integrity, availability, and
resilience of processing systems and services”
28. Article 32(1)(d) which states organisations should have:
“a process for regularly testing, assessing and evaluating the
effectiveness of technical and organisational measures for ensuring
the security of the processing.”
29. Our investigation found infringements in relation to the security
requirements of the UK GDPR, and these are set out below.
Article 32(1)
30. ACRO did not have the correct organisational measures in place to
ensure a level of security appropriate to the risk as per Article
32(1). ACRO did not clearly define who was responsible for
monitoring for required security patches. ACRO’s web development
supplier were responsible for the
application of security patches, but not for identifying when
patches were required. ACRO itself did not monitor for required
security patches, meaning that there was an absence of oversight
for this important security control. This demonstrated failings in
the organisation’s wider obligations under the UK GDPR.
9NON-CONFIDENTIAL - FOR PUBLICATION
Article 32(1)(b)
31. ACRO were not ensuring the ongoing confidentiality, integrity and
resilience of their systems as per Article 32(1)(b). ACRO did not
have the appropriate technical and organisational measures in
place to ensure the level of security appropriate to risk.
32. Unpatched Content Management System (CMS)
33. ACRO’s website was built using the Kentico CMS. Between
September 2019 - March 2023, this was running on version 12.0.0.
This version of Kentico CMS had multiple known vulnerabilities at
the time of the incident. The forensic investigation did not specify
which vulnerability was exploited, however it is highly likely that
the threat actor gained initial access by exploiting an unpatched
Kentico software vulnerability.
9
34. Cumulative security hotfixes were released by Kentico between
September 2019 - July 2023. None of these security hotfixes were
applied, meaning the ACRO website remained on an unpatched and
vulnerable version.
35. ACRO did not provide the ICO with evidence demonstrating that
the security risks associated with known Kentico CMS
vulnerabilities had been subject to documented risk assessment or
formal governance processes in relation to CMS patching.
36. Content Management System Patching Responsibility
8
9National Vulnerability Database – Kentico Xperience 12.0.0
A vendor issued software update designed to quickly address a specific problem, usually a
critical security vulnerability.
10NON-CONFIDENTIAL - FOR PUBLICATION
37. ACRO could not demonstrate clear accountability for identifying
required security patches and hotfixes for Kentico CMS during the
ICO’s investigation.
38. ACRO’s Managed Service Provider were responsible for
Operating System (OS) patching and server maintenance where
12
monthly Microsoft security updates were applied to production
13
and staging servers . This excluded patching for the Kentico CMS
as role was limited to infrastructure.
39. Application of Kentico CMS patches and hotfixes were assigned to
as evidenced by an email exchange between ACRO and
dated 14–20 February 2020, which explicitly confirmed that CMS
updates fell within remit under the support agreement.
While this confirmed responsibility for implementing and
applying Kentico CMS patches and hotfixes, it did not establish
whether was obligated to actively monitor for these.
40. The ambiguity around who was accountable for identifying
necessary Kentico CMS patches created a gap where patches and
hotfixes were missed which ultimately left ACRO’s website
vulnerable.
41. Patching Policy
42. ACRO did not provide a documented patching policy covering CMS
updates, despite the ICO requesting this during the investigation.
10The core software that manages a computer’s hardware and software resources, providing a
platform for applications to run.
11The process of applying vendor issued updates to an operating system.
12The live environment where the application or website is fully deployed and accessible to end
users.
13A pre-production environment that closely mirrors the production setup.
11NON-CONFIDENTIAL - FOR PUBLICATION
43. As a result, ACRO could not demonstrate how vulnerabilities were
identified, prioritised and/or tested, nor how responsibility for
these activities was assigned or assured.
44. The absence of such a policy reinforced the fragmented and poor
approach to patch management, leaving critical responsibilities
unclear.
45. Industry guidance is clear in relation to patching and vulnerability
management:
46. NCSC’s 10 Steps to Cyber Security published in May 2021 includes
guidance on vulnerability management, including updating
software to address vulnerabilities.
“Ensure all systems have a software update strategy. For devices
that are not automatically updated, this should detail how and
when updates get applied, and who is responsible for doing and
checking the updates. The strategy should account for system
availability requirements and relevant dependencies, while aiming
to minimise the length of time before updates are applied.” “it is
important (and essential for any systems that are exploitable from
the internet) to install security updates as soon as possible to
protect your organisation.”
47. NCSC’s Cyber Essentials v3.0 published in January 2022 includes
an objective for Security Update Management.
14
1510 Steps to Cyber Security - NCSC.GOV.UK
Cyber Essentials - Requirements for Infrastructure v3.0.pdf
12NON-CONFIDENTIAL - FOR PUBLICATION
“Ensure that devices and software are not vulnerable to known
security issues for which fixes are available.”
48. Response to Security Alerts
49. The infrastructure that supported the ACRO public facing website
had Trend Micro antivirus software (Trend Micro) installed at the
time of the incidents. This was designed to detect and quarantine
17 18
malware, such as credential harvesting tools and backdoors , by
scanning files and monitoring system activity.
50. While Trend Micro did successfully detect and quarantine several
threat actor tools during the incidents, the alerts that were
generated were not reviewed or acted upon.
51. ACRO advised the ICO that, due to
it was unable to establish what business
processes existed for the assessment or handling of security alerts
at the relevant time. Nor could it identify which roles were
responsible for reviewing or escalating such alerts. As a result, the
ICO was not provided with evidence demonstrating that Trend
Micro alerts relating to the detection and quarantining of known
threat actor tools were assessed, escalated, or investigated at the
time they were generated.
16A solution developed by Trend Micro, designed to protect computers and networks from
malware, viruses, ransomware, and other threats.
17A technique where a threat actor collects usernames, passwords, and other authentication
data from a target system or user.
18A hidden method of bypassing normal authentication or security controls to gain
unauthorised access to a system, application, or network.
13NON-CONFIDENTIAL - FOR PUBLICATION
52. Had the alerts been investigated by ACRO at the time, and an
appropriate response conducted, it is likely that further malicious
activity could have been prevented.
53. System and Security Monitoring
54. There was some level of monitoring in place as undertook
monitoring activities in line with its contractual obligations.
were contracted to provide ACRO with support,
maintenance and management of ACRO’s environment.
This environment contained a virtual firewall, virtual web servers
and virtual SQL servers which together supported the ACRO
public website and staging websites. ACRO did not subscribe to
SIEM service. documents
were provided to ACRO by these documents included a
section that provided an opportunity to
highlight any ongoing security issues, such as patching and
security incidents.
55. As described above at paragraphs 49 – 52, there were multiple
antivirus detections of malicious software during the incidents. On
23 February 2023 Trend Micro detected and quarantined four
attempts to install the known credential harvesting tool
Mimikatz . However, the February 2023
document does not include any reference to the
malicious files quarantined by Trend Micro antivirus, this is
despite being required by ACRO to reboot the affected
server.
19
A solution that provides real time monitoring, analysis, and management of security events
20ross an organisation’s IT infrastructure.
https://attack.mitre.org/software/S0002/
14NON-CONFIDENTIAL - FOR PUBLICATION
56. Despite Trend Micro successfully detecting and quarantining
threat actor tools on multiple occasions, these alerts were not
investigated or acted upon by any involved party.
57. The forensic investigation identified multiple historic Trend
Micro Antivirus alerts related to detected and quarantined
attacker tools. These alerts provided an early warning to the
ongoing attack but were not reviewed or acted on.
58. ACRO advised the ICO that it could not establish which roles
previously held responsibility for monitoring security alerts
which occurred prior to and during the period of Group A threat
actor activity.
59. The ambiguity around the role and responsibility of responding to
security alerts, and the failure to act up the generated security
alerts resulted in the threat actor being able to carry out its
activity undetected.
60. Industry guidance is clear in relation to monitoring and visibility:
21
61. NCSC’s 10 Steps to Cyber Security published in May 2021
includes guidance on logging and monitoring.
“the main priority should be the ability to respond to incidents
and to do this, logs are required.”
“Collecting logs is essential to understand how your systems are
being used and is the foundation of security (or protective)
21
10 Steps to Cyber Security - NCSC.GOV.UK
15NON-CONFIDENTIAL - FOR PUBLICATION
monitoring. In the event of a concern or potential security
incident, good logging practices will allow you to retrospectively
look at what has happened and understand the impact of the
incident. Security monitoring takes this further and involves the
active analysis of logging information to look for signs of known
attacks or unusual system behaviour, enabling organisations to
detect events that could be deemed as a security incident, and
respond accordingly in order to minimise the impact.”
62. NCSC’s Secure Design Principles published in May 2019 22 states:
“Ensure you log enough to perform root cause analysis in event
of a failure. Will your logs hold the data you need to work out
whether a failure happened as a result of a breach? Both
infrastructure and application level logs may be needed.”
“As well as collecting logs and capturing relevant events, you
should ensure that the integrity of your logs would be maintained
in event of a breach. The attacker should not be able to cover
their tracks.”
63. The NIST 800-61 Rev 2 Computer Security Incident Handling
Guide (3.2.4 – Incident Analysis) published in August 2012 23
states:
“the incident response team should work quickly to analyze and
validate each incident, following a pre-defined process and
documenting each step taken. When the team believes that an
incident has occurred, the team should rapidly perform an initial
analysis”
22
23Secure design principles | National Cyber Security Centre
SP 800-61 Rev. 2, Computer Security Incident Handling Guide | CSRC (nist.gov)
16NON-CONFIDENTIAL - FOR PUBLICATION
24
64. CIS Control 13 Network and Monitoring Defence published in
2021 states:
“Centralize security event alerting across enterprise assets for log
correlation and analysis. Best practice implementation requires
the use of a SIEM, which includes vendor-defined event
correlation alerts.”
Article 32(1)(d)
65. ACRO did not maintain effective processes for testing or
evaluating its security measures as per Article 32(1)(d). ACRO
operated without a documented patching policy and continuous
security monitoring, leaving the organisation unable to verify
whether its technical and organisational measures were effective
at any point during the periods of compromise.
66. ACRO lacked a structured process for analysing security alerts, as
demonstrated by the failure to investigate multiple Trend Micro
antivirus alerts indicating the presence of threat actor tools.
67. ACRO advised the ICO that it was unable to identify which roles
previously held responsibility for reviewing such alerts
This lack of defined
responsibility meant that alerts were not reviewed, escalated, or
acted upon, preventing ACRO from identifying or containing
ongoing threat actor activity.
24
CIS stands for the ‘Center for Internet Security’, a nonprofit organisation dedicated to
improving cybersecurity for public and private sector entities worldwide.
17NON-CONFIDENTIAL - FOR PUBLICATION
V. DECISION TO ISSUE THIS REPRIMAND
68. Taking into account all of the circumstances of this case, including
the nature, duration and seriousness of the infringements
identified, as well as the mitigating factors and remedial steps
taken by ACRO following the incidents, the Commissioner considers
that it would be a reasonable and proportionate exercise of his
powers to issue a reprimand to ACRO for infringements of Articles
32(1), 32(1)(b) and 32(1)(d) of the UK GDPR, as set out above,
and that a reprimand would be an effective, proportionate and
dissuasive measure.
Dated: 7 August 2026
Signed: …………………………………
Jonathan Balmforth
Group Manager, Civil and Cyber Investigations
Information Commissioner’s Office
Wycliffe House
Water Lane
Wilmslow
Cheshire
SK9 5AF
18




