Personal Breach Notification Guidelines Analysed

Kuan Hon has carefully analysed the Article 29 Working Party Guidelines on personal breach notification under the GDPR. Note that the article covers the version that was put out for consultation in November 2017, and that the final version may differ

This article summarises WP250, guidance from EU regulators WP29 on breach notification to supervisory authorities and data subjects under the GDPR (Arts.33-34). The Annex highlights some areas where the guidance may increase confusion about technical security matters. For some specific problems under WP250, please see my IAPP article. 


 ·        Be prepared – unsurprisingly, WP250 urges controllers’ and processors’ advance implementation of incident response plans for handling personal data breaches (PDBs).

·        Scope – plans should cover allocating internal operational responsibilities (with processes to funnel incident-related info to the right people), detecting/establishing PDBs, incident management including appropriate internal escalation/reporting, containment/recovery/ remediation, assessing likely risk to individuals (see later - likelihood of no risk, risk or high risk) and other actions, notably making any necessary notifications to the supervisory authority (SA) and affected individuals, to which SA, etc. All this should happen “soon after” the initial alert, save in “exceptional cases”. It’s “useful” for GDPR compliance to show employees were told about these plans and know how to respond.

·        DPIA - a prior data protection impact assessment might have considered potential risks from PDBs, but each actual PDB requires specific risk assessment.

·        DPO - any data protection officer should be involved in PDB notifications and subsequent SA investigations.

·        Lawyers - not mentioned in WP250 (why would it?), but involve ASAP data protection/ security lawyers (ideally, covered in the plan) to help preserve legal privilege for forensic reports etc. in case of future claims/litigation/regulatory sanctions, and advise on notifications, damage mitigation and fines reduction.

·        Security measures (Art.32) must include measures to “detect, address and report a breach in a timely manner” (also Rec.87). If encrypting, consider “quality” [algorithm strength, key size?], implementation, outdatedness; change “default keys” [default admin passwords?], etc. If a DPIA suggests particular security software, but a vulnerability becomes known, reassess the software “as part of an ongoing DPIA”. Take backups, as well as encrypting whenever possible.

·        Potential “double whammy” – organisations can be fined for not notifying personal data breaches, and for inadequate security measures: “…they are two separate infringements”.

·        Triple whammy? – SAs can order controllers to notify individuals (Arts.34(4), 58(2)(e)). Disobey on pain of a 4%/€20m fine (Art.83(6)).

·        Good encryption good – organisations can escape notifying, not only individuals, but maybe even SAs, of PDBs affecting encrypted data, as the breach is “unlikely” to result in risks to individuals, e.g. losing a securely-encrypted mobile - but only if the encryption applied was appropriate, properly implemented, and not e.g. using an outdated algorithm.

·        Prompt investigation vital – plans should enable prompt investigation of incidents to determine whether any PDB occurred and, if so, remediate and notify. Otherwise, regulators may assume earlier “awareness” of breaches (and possible Art.33 infringement). Therefore, controllers must act on “any initial alert” (from whatever source), not ignore them.

·        Awareness – a “short” period of investigating an incident is allowed before controllers are considered “aware”. But as soon as your processor is “aware”, “in principle” you’re aware (and your 72-hour notification clock begins running) from that same point in time!

·        PDBs at processors – Art.33(2) already requires processors to notify their controllers. However, WP250 recommends specific arrangements: controller-processor contracts’ mandatory terms on processors assisting controllers with breach notification (Art.28(3)(f)) should specify how processors should notify controllers.

·        Notifying “without undue delay”

·        Regulators consider processors should give “immediate” notification of PDBs to all their affected controllers, with further info in phases when available.

·        If controllers notify affected individuals (when that’s required) “without undue delay”, that means “as soon as possible”, or as soon as “reasonably feasible”.

·        Don’t forget Rec.87: what’s not “undue delay” in one situation may be in another, depending on the PDB’s nature, gravity, and consequences/adverse effects for individuals.

·        Not knowing precise info, e.g. exact numbers of individuals affected, is no excuse for delayed notification.

·        If an incident affects multiple individuals similarly, strictly each is reportable. However, WP29 will accept a meaningful “bundled” notification covering similar personal data breached in a similar manner over a short period, whether after or within 72 hours.

·        Processors can notify for their controllers – if the controller-processor contract authorises it. But controllers retain legal responsibility. So, they might not want to delegate notifications to processors.

·        Notify what? – under WP250:

·        Art.33(3)’s “categories” of data subjects means e.g. children/other vulnerable groups, disabled people, employees, customers; categories of records means health data, educational records, social care info, financial details, bank account numbers, passport numbers etc.

·        Describing “likely consequences” includes indicating risk categories: identity theft, fraud, financial loss, threat to professional secrecy. Focus on adverse effects.

·        Provide approximate numbers if still unknown, then details later.

·        If more info will follow, WP250 recommends telling the SA so. However, “The supervisory authority should agree how and when additional information should be provided” seems unrealistic (and isn’t required by the GDPR). SAs shouldn’t dictate how quickly forensics investigators must discover info, investigators should be allowed to take whatever time they need to do their jobs properly.

·        Provide more info than Art.33(3) specifies, if desired.

·        “Shop the processor?” – Processors may want controller-processor contracts to require controller notifications to be accurate and fair (some controllers may just blame processors even if unwarranted?), and give processors some say/role in controllers’ notification processes!

·        SAs can request further info.

·        One purpose of notifying SAs within 72 hours is for advice on whether to notify individuals (see below).

·        Notify, de-notify… - update the SA on ascertaining that the incident was contained and no breach occurred. There’s no penalty for reporting something that transpires not to be a breach. Overall, WP250 may drive organisations to notify SAs of all incidents within 72 hours “just in case”. Will overwhelmed SAs “take back” some of WP250 in a year…?

·        Notifying individuals if “likely” “high risk” – must be considered independently of SA notification. Exceptionally, notify individuals before SAs.

·        A “description” of measures to address/mitigate (Art.34(2)) may include:

·        E.g. that “after having notified the breach to the relevant supervisory authority, the controller has received advice on managing the breach and lessening its impact.”

·        Where appropriate, specific advice to individuals to protect themselves e.g. resetting passwords where access credentials were compromised.

·        Provide more info than Art.33(3) specifies, if desired.

·        Notify affected individuals directly; if that involves “disproportionate effort”, use public communication or similar: email, SMS, “direct message”, website banners/notification, post, prominent print ads (a press release/corporate blog alone isn’t good enough). WP250 recommends using several channels (but not one compromised by attackers!)

·        Alternative formats/languages may be needed.

·        Consider consulting the SA on appropriate notification content/channels.

·        “Get-outs” from notifying individuals:

·        Controllers must be able to demonstrate they meet a “get-out”, including as risks change over time.

·        Potential 2%/€10m fine if individuals aren’t notified when the SA thinks they should be.

·        Breached data being “unintelligible” to unauthorised persons is said to include “state-of-the-art” encryption - suggesting that outdated/poor encryption won’t be enough to avoid notification.

·        Steps to ensure “high risk” is no longer likely – include identifying and acting against whoever accessed data before they could “do anything with it”.

·        “Disproportionate effort” – e.g. where contact details were lost in the breach or never known. “Technical arrangements” could make on-demand information about the breach available to individuals that the controller can’t otherwise contact.

·        Risk assessment – vital following awareness of breach. Knowing likelihood and potential severity of impacts on individuals helps (1) containment [mitigating risks to individuals? Cf. breach containment], and (2) determining whether/who to notify. Risks are higher with greater severity and/or likelihood. “If in doubt, the controller should err on the side of caution and notify.”

·        “High risk” – is where the breach may lead to physical, material or non-material damage, e.g. discrimination, identity theft/fraud, financial loss or reputational damage. Damage “should be” considered “likely” if breached data are “special category” or criminal convictions/offences data.

·        Factors include:

·        Breach type e.g. confidentiality or loss; nature (name/address vs. adoptive parent’s address), sensitivity (more sensitive is higher risk), volume of data, number of affected individuals (greater data volume/number, higher risk; but, “a small amount of highly sensitive personal data can have a high impact on an individual, and a large range of details can reveal a greater range of information about that individual”). Combined data’s more sensitive than one “piece” (e.g. health data plus identity documents/credit card details). Stopped deliveries (holidays) may indicate vulnerable homes. A little highly sensitive data can be very impactful; a large “range” of data, very revealing.

·        Identifiability – how easily can someone accessing compromised data identify individuals e.g. by matching with other info? Much depends on context, public availability of related details, etc. Pseudonymisation not just encryption can reduce identifiability.

·        Severity of consequences – affected by nature of data e.g. special categories; vulnerable individuals; whoever accessed data (if known, e.g. disclosed in error, or otherwise trusted to return/destroy data, cf. actors with malicious/unknown intentions). EU security agency ENISA’s severity assessment methodology may be useful when formulating response plans. Longer-term consequences have greater impact.

·        Characteristics of individuals/controllers – e.g. risks may be greater with children/vulnerable individuals; and with medical controllers with health data (cf. newspaper mailing lists).

·        Cross-EU breaches – notify the lead SA. Ideally, indicate which other Member States’ individuals are affected and notify SAs there too.

·        Accountability and record-keeping – controllers must document even unnotifiable breaches (Art.33(5)), e.g. an internal breach register (or in general processing records, provided all breach info is easily extractable on SA request) - including cause, what happened, affected data, effects/consequences, remediation implemented. 2%/€10m fine (and regulatory orders) possible for not documenting breaches. WP250 recommends recording reasons for post-breach [“incident”?] decisions, justifications for not notifying (including why it’s considered unlikely to result in a risk, proof of meeting any “get-outs”), reasons for delayed notification, proof of notifications to affected individuals.

·        Breach notification under other laws – other requirements may also apply e.g. EIDAS Regulation, NIS Directive, professional duties and (though not mentioned) financial services regulation. 

To conclude, I believe that, given WP250, in practice organisations will be taking the approach of “If in doubt, shout it out!” There’s no penalty for crying wolf, but there is for not notifying when regulators consider you should have. 

Will regulators change their minds if they get “too many” notifications, many of which may be about only minor breaches? We shall see. 

Dr W Kuan Hon, Director, Privacy, Security & Information, Fieldfisher, licensed under CC-BY (please link to this article). This article represents Kuan’s personal opinions and are not necessarily shared by any organisation with whom Kuan may be associated.

Annex – Other technical security issues 

WP250 could exacerbate misinformation about security issues, if it remains unchanged. In particular, it seemingly refers to everything as “breaches”, but it should address incidents and breaches separately. 

Examples are below. 



WP250 p.6 outlines the three well known types of security breaches, the “CIA triad”, as follows, noting that one breach (or incident) could affect any combination of them:

·        “Confidentiality breach” – unauthorised or accidental disclosure of, or access to, personal data.

·        “Availability breach” – accidental or unauthorised loss of access to, or destruction of, personal data.

·        “Integrity breach” – unauthorised or accidental alteration of personal data.


Permanent loss/destruction, including accidental or unauthorised deletion or, for securely encrypted data, losing the decryption key, certainly affects availability.


But clearly, and perhaps more importantly, it also affects integrity. “Integrity breach” includes data loss or destruction – e.g. see the US FISMA or FIPS199 (detailed CIA comparisons are in my book, table 7.1). Also, Art.5(1)(f), described as “integrity and confidentiality” (not “availability”), mentions “loss” and “destruction”, strongly suggesting that lawmakers think loss/destruction affects integrity.


Accordingly, “or destruction of” falls better under Integrity than Availability.

“Furthermore, it should be noted that although a loss of availability of a controller’s systems might be only temporary and may not have an impact on individuals, the fact that there has been a network intrusion could still be considered a potential confidentiality breach and notification might be required. Therefore, it is important for the controller to consider all possible consequences of a breach.” (p.7)

DDOS attacks, interfering with authorised users’ availability, are often used as a smokescreen to distract IT/security staff, enabling criminals to infiltrate the network to steal data while staff are occupied dealing with the DDOS.


A DOS/DDOS attack, alone, does not normally affect confidentiality. It may be followed by a confidentiality attack through some other means (e.g. malware), but a DOS attack does not itself involve a confidentiality breach.

“The focus of the notification requirement is to encourage controllers to act promptly on a breach, contain it and, if possible, recover the compromised personal data, and to seek relevant advice from the supervisory authority.” (p.13)

It depends on the type of incident. An organisation can “recover” compromised data from any backup if someone destroyed or corrupted data (integrity breach). “Recovering” stolen data, to ensure unauthorised persons can no longer access it (confidentiality breach), is much harder, especially if the attacker has already published data online.

“WP29 also explained this would similarly be the case if personal data, such as passwords, were securely hashed and salted, the hashed value was calculated with a state of the art cryptographic keyed hash function, the key used to hash the data was not compromised in any breach, and the key used to hash the data has been generated in a way that it cannot be ascertained by available technological means by any person who is not authorised to access it.” (p.15)

Hashing involves a “one-way” scrambling of data using an algorithm. It doesn’t generally use keys.


The main exception is keyed hashing of messages (HMAC). But the aim there isn’t confidentiality, it’s integrity – verifying and proving that a message (e.g. email) hasn’t been altered during transmission.


Furthermore, it’s unclear what “similarly” would “be the case” here – that a breach in such circumstances needn’t be notified?

“Consequently, if personal data have been made essentially unintelligible to unauthorised parties and where the data are a copy or a backup exists, a confidentiality breach involving properly encrypted personal data may not need to be notified to the supervisory authority. This is because such a breach is unlikely to pose a risk to individuals’ rights and freedoms…” (p.16)

This WP250 sentence confuses the issues.


Unauthorised access to data affects confidentiality (not integrity or availability). Data destruction integrity and availability (not confidentiality, unless the intruder also accessed intelligible data before destroying the data. Unauthorised access does not necessarily involve destruction, and vice versa (again, please see my book, Chapter 7). But the WP250 sentence conflates the two.


Encryption address confidentiality, while backups address integrity and availability (again see my book, Chapter 7).


A breach involving properly encrypted data may not even be a confidentiality breach. This depends on the efficacy of the encryption etc., not whether a backup exists.


Having backups does not make a breach affecting unintelligible personal data a non-notifiable confidentiality breach, as this WP250 sentence implies. Lack of backups affects integrity and availability, not confidentiality.


To avoid confusion, this sentence should probably read, “unauthorised access to properly encrypted personal data may not…” (instead of, “a confidentiality breach involving properly encrypted personal data”), and “where the data are a copy or a backup exists” should be deleted.

“Furthermore, it should be noted that if there is a breach where there are no backups of the encrypted personal data then there will have been an availability breach, which could pose risks to individuals and therefore may require notification.” (p.16)

It depends on the nature of the breach. Sometimes intruders just access/copy data. Sometimes, they also interfere with it, e.g. ransomware encryption.


This WP250 sentence doesn’t specify what kind of incident it envisages, unfortunately.


Unauthorised access to securely-encrypted data (with no key access), would not involve a notifiable confidentiality breach.


The reference to “no backups” makes sense only if the breach involved data loss, destruction or alteration – not access alone. But that’s an integrity breach, notifiable as such (no need to discuss availability breaches). Mere unauthorised access to encrypted data, without any data destruction etc., would not involve an integrity breach.

“A breach that would not require notification to the supervisory authority would be the loss of a securely encrypted mobile device, utilised by the controller and its staff. Provided the encryption key remains within the secure possession of the controller and this is not the sole copy of the personal data then the personal data would be inaccessible to an attacker.” (p.16)

Again, this confuses confidentiality and integrity.


Inaccessibility to an attacker depends on the encryption key remaining secure. If the attacker doesn’t have the key, there’s no confidentiality breach.


If the mobile did not contain the controller’s sole copy of the data, because it had been backed up, then there’s no integrity breach.


Therefore, the last sentence should instead read, “Provided the encryption key remains within the secure possession of the controller then the personal data would be inaccessible to an attacker (so this would not be notifiable as there was no confidentiality breach), and provided this is not the sole copy of the personal data the data would remain accessible to the controller (so this would not be notifiable as an integrity breach)”.

“Identification may be directly or indirectly possible from the breached data, but it may also depend on the specific context of the breach, and public availability of related personal details. This may be more relevant for confidentiality and availability breaches.” (p.21)

Why is identifiability considered relevant to availability breaches?

 Inconsistency on p.14 – “Depending on the circumstances, it may take the controller some time to establish the extent of the breaches and, rather than notify each breach individually, the controller instead organises a meaningful notification that represents several very similar breaches, with possible different causes. This could lead to notification to the supervisory authority being delayed by more than 72 hours after the controller first becomes aware of these breaches.”

Cf. “However, to avoid being overly burdensome, the controller may be able to submit a “bundled” notification representing all these breaches, provided that they concern the same type of personal data breached in the same way, over a relatively short space of time.”

The italicised words contradict each other – “different” is the opposite of “same”. It should probably read “possibly similar causes”. 

Annex B is meant to provide “a non-exhaustive list of examples of when a breach may be likely to result in high risk to individuals and consequently instances when a controller will have to notify a breach to those affected.” However, most (not all) the examples in Annex B simply state, “if…”, and/or “…depending…”. This approach seems circular. Annex B would be more helpful if WP29 explained which situations it thinks is a “risk” or a “high risk”, rather than referring back to “if”, etc. Otherwise, Annex B only gives examples of some possible types of incidents or breaches, without providing guidance on when notification should be made to SAs and/or individuals. E.g.:

·        Example ii – report “depending… and if the severity… is high”, and “If the risk is not high…”.

·        Example iv – report to SA “if there are potential consequences”, report to individuals “depending on the nature…”

·        Example v – “if there is a high risk”, etc. etc. 

P.26 “However if it is later compromised” would be clearer if it read “However if the key is later compromised”.

Published: 2017-12-20T12:20:00


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