Disaster recovery - disgruntled employee

Security risks to enterprise systems are not limited to external attackers. As organisations scale, increased headcount and staff turnover can introduce internal risks. While the vast majority of employees maintain a constructive relationship with their employer, rare cases of hostility or negligence must still be accounted for in a resilient disaster recovery (DR) strategy.

An effective DR design needs to consider not just system failure or external compromise, but also the possibility of internal sabotage or credential misuse. A critical vulnerability arises when the same individuals or systems have full access to both the primary data and its backups. In such a setup, a disgruntled employee or an external attacker who gains internal credentials could erase all copies of essential data, including backups.

To mitigate this, a secure backup strategy should separate responsibilities and access. Those who manage or write to the source data should not have permissions to alter or delete the backup destination. Conversely, those responsible for the backup infrastructure should not have access to the original data. This separation of duties reduces the risk of full data loss from any single compromise.

A recent implementation illustrates this principle. The client was using AWS S3 buckets to store large volumes of enterprise data. To improve their resilience, a separate AWS account was provisioned solely for disaster recovery. S3 replication was configured to mirror data into this DR account, with the replicated buckets hosted in a different European region to ensure regional isolation.

Several safeguards were added to enhance the design:

• Monitoring and alerting were configured to detect any interference with replication at the source account.

• S3 versioning was enabled on all buckets to preserve all file changes, including deletions. This ensured that even if a file was removed at the source, historical versions could still be recovered.

• Recognising the implications for GDPR and data retention policies, a controlled process was introduced for legitimate deletions, balancing compliance with security.

• Most users were restricted from deleting versioned objects, adding another layer of protection against accidental or intentional data loss.

  
  

A common failure in disaster recovery design is overlooking the risk of backup pipelines being disabled or tampered with silently. A secure design assumes a hostile actor's perspective - considering all vectors for turning off, corrupting, or deleting backups - and puts in place visibility and control mechanisms to counter those risks.

Finally, recovery procedures were documented and tested. While automation is valuable, periodic manual verification was also scheduled to ensure end-to-end recoverability.

Following this engagement, the client had confidence that their backup system was resilient not only to external attacks but also to insider threats or misuse of administrative access. The result was a mature and balanced disaster recovery design tailored for real-world risks.