Data leakage, backup and recovery

Data leakage

• Any sort of unauthorized disclosure of sensitive information from anyone/any system.
• Includes emails, malicious links, device theft etc.
• Data leakage leads to
  • loss of trust e.g. trust to governments decreased during late years
  • loss of profit e.g. Sony lost profit of their movies after they were leaked before publishing

Data leakage threats

External threats

• Corporate espionage, phishing, malware
• Business partners, consultants when company outsources
  • Less surveillance than own employees.

Internal threats

• Also known as insider threats
• Dangers are greater than external threats as they'll have greater access to the company
• See also insider attacks
• E.g. eavesdropping, shoulder surfing, dumpster diving can be used to acquire data.

Data loss prevention

• Also known as DLP
• Identification and monitoring of important information that is not to be shared outside the organization.
• Can block, notify the sender or lets admins to analyze, react and report to sensitive data in transit.
• Important tool for enterprise message systems
• Uses different techniques of data access control
  • E.g. when e-mailing where content is scanned for fingerprints, classifications and bank account numbers.

Data backup

• Process of making a duplicate copy of data that already exists.
• Protects against data loss and corruption as it can lead to great financial damages.
• No backup = Far more suspectable to all sorts of attacks, especially ransomware.

Backup mediums

Magnetic tapes

• Oldest form, still used by many enterprises.
• Retention time: ≈30 years
• 📝 To pull anything off the tape, you have to fast-forward to wherever the correct file is stored
  • Good for restoring systems in one go.
  • Bad for incremental backups or storing a few files.
  • ❗ Only way to tell if backups are working is to fully restore from the tape and check if it's correctly restored.

Optical disks

• 2 to 3 times slower than hard drives
• Retention time: ≈25 years

Hard disks

• Cheaper, easily accessible
• Less stability than magnetic tapes
• Retention time: ≈9-20 years

SSD disks

• Includes also usb drives known as Flash storage or thumb-drive.
• Resistant to shock, temperature, being run through the washing machine
• Retention time: ≈10 years

Cloud storage

• Requires little infrastructure
• Depends on stable internet connection
• No retention time, high reliability

SD and micro-SD

• Little capacity and pricy.
• Retention time: ≈10 years

Steps of data backup strategy

1. Identify important data
   • because backing-up everything is too costly and takes up much storage.
2. Choose appropriate backup media
   • Reliable, solid, preferably cheap
   • E.g. USBs or portable media for personal users, and HDD/SDDs for companies for more speed.
3. Choose the appropriate backup strategy
   • Check features such as scheduling, monitoring file changes to update back-ups, protocols, integrations...
   • Paid vs Free
     • Free requires more knowledge and work, training costs (one time)
       • E.g. in Linux, set cron job from point A to B
     • Paid versions has recurring license costs including training
4. Choose appropriate RAID levels
   • RAID 1
     • 2 disks
     • All that are written in disk A is also written to B, if one disk fails, other works
   • RAID 5
     • 3 disks
     • If A fails you can reconstruct based on data in B and C
   • RAIDing is not only for backups, can also use for faster read and writes
     • E.g. BIG = Everything is seen as one drive. File is written two all of them. Crazy write & read speeds. If single disk dies all data is gone.
5. Choose the appropriate backup method
   • Cold backup
     • Performed while system is not in use.
     • E.g. at nights, during weekends.
   • Hot backup
     • Performed when system is still used.
     • E.g. you type a document, power shortage happens but it's still saved.
   • Warm backup
     • Hybrid of the two.
     • Period backups while system is in use, but you might lose longer time period than hot backup.
6. Choose the appropriate backup locations
   • Three options:
     1. On-site: Same building / room
        • Susceptible to same types of problems like other servers.
        • If there's a breach, fire or earthquake = all data are gone
     2. Off-site: backup is performed at a remote location
     3. Cloud:
        • Most secure: most cost effective and safe where data won't be loss, no electricity, no hardware, no maintainable.
        • Can be replicated in same building, different buildings in same data center or different regions.
        • Can have privacy/trust issues: encrypt
7. Choose the backup type
   • Full backup: Costly, you back up everything
   • Incremental backup
     • Backs-up on each change of the previous back-up
     • When restoring, you need to restore everything from the first full back-up
   • Differential backup:
     • Back-ups on difference to the initial backup on each backup.s
     • Faster restoring time as you only need the last point and the initial full back-up
8. Appropriate backup solution: Combination of all of this
9. Perform a recovery test
   • Ensure you can recover a data that's lost with DR tests e.g. twice a year.
   • Recovery drill
     • Simulating data tier outage
     • Recovering
     • Validate application integrity post recovery

Data recovery

• Recovering lost data
• Reasons
  • Accidental lost e.g. • natural disaster • corrupted data
  • Or can be intentionally destroyed
• DR stands for "Disaster Recovery"
• Most of data is recoverable but you can have recovery failure if backed up data becomes corrupt.