Data States and Data Remanence – Rest Motion or Transit

Dec 21, 2020

Data at rest refers to data stored on media such as hard drives, removable media, or backup tapes. Data at rest can be encrypted for protection.

Data in motion or data in transit refers to data that is moving or being transmitted to another device. Two concepts are presented in the CBK that relate to protecting data in motion:

End-to-end encryption – which refers to encryption that is established between endpoints, typically as seen when accessing a website using HTTPS. The encryption is established between the web server and the user’s device. Certain information is visible to eavesdroppers such as routing information.
Link encryption – which refers to a process that decrypts and re-encrypts the data packet at each node. Routing information is invisible to eavesdroppers when using this method.

Data in use refers to data in process or data that is being used by an application or function. Since data in use is cleartext, the use of an enclave is recommended in order to separate it from other components of the architecture.

Data Remanence

Data remanence is the data that remains after deletion, which creates a risk. To mitigate the risk of malicious data recovery, physical destruction is always the best method. Other methods of dealing with remanence include several terms:

Clearing
Purging
Destruction
Degaussing
Sanitizing
Overwriting
Wiping
Encryption

Let’s try to simplify this. There are basically three categories of dealing with data remanence:

Clearing
Purging
Destruction

Clearing is a strong method of data removal, typically it involves wiping or overwriting the data with zeroes or ones; data may be recoverable under this method.

Purging is a stronger permanent method that can include methods such as sanitizing or degaussing (exposing the media to strong magnetically charged fields); data is not considered recoverable by any known methods.

Destruction is the strongest method and includes shredding, pulverizing, burning, and encryption.

To memorize this, repeat the phrase “Cow, Pig, Sow,” or “CP SOW.” Repeat it again and think of a farm you visited or one that you saw in a movie. Now repeat the following mnemonic:

Clearing Can (be recovered)

Purging is Permanent

Sanitizing is the Same (as purging)

Overwriting with Oh’s

Wiping is Writing (overwriting, that is)

Notice how the letters match to help you remember. It seems silly, yes, but this is the key.

So here’s the phrase to keep repeating, once again:

Cow Pig Sow; CPSOW, Clearing Can, Purging is Permanent, Sanitizing Same, Overwriting Oh’s, Wiping is Writing. Repeat this over and over, and consider copying it onto a memorization sheet.

Here’s a video to help illustrate it:

Cloud-based data remanence can be addressed through encryption.

When it comes to non-magnetic drives, such as solid state drives (SSD) the best method (aside from physical destruction) is a combination of overwriting, purging, and encryption, or crypto-erase, which means to encrypt the drive and throw away or destroy the key.

A few more terms that you need to be aware of for destruction are:

Use of corrosive chemicals
Phase transition, which means that both temperature and pressure are applied in order to change the state of the drive
And CURIE temperature, which applies to magnetic disks – curie temperature is the process of heating the drive to a point where it loses its magnetic properties

Destruction methods are discussed in NIST special publication 800-88

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OWASP TOP !0

Injection. Injection flaws, such as SQL, NoSQL, OS, and LDAP injection, occur when untrusted data is sent to an interpreter as part of a command or query. The attacker’s hostile data can trick the interpreter into executing unintended commands or accessing data without proper authorization. Broken Authentication. Application functions related to authentication and session management are often implemented incorrectly, allowing attackers to compromise passwords, keys, or session tokens, or to exploit other implementation flaws to assume other users’ identities temporarily or permanently. Sensitive Data Exposure. Many web applications and APIs do not properly protect sensitive data, such as financial, healthcare, and PII. Attackers may steal or modify such weakly protected data to conduct credit card fraud, identity theft, or other crimes. Sensitive data may be compromised without extra protection, such as encryption at rest or in transit, and requires special precautions when exchanged with the browser. XML External Entities (XXE). Many older or poorly configured XML processors evaluate external entity references within XML documents. External entities can be used to disclose internal files using the file URI handler, internal file shares, internal port scanning, remote code execution, and denial of service attacks. Broken Access Control. Restrictions on what authenticated users are allowed to do are often not properly enforced. Attackers can exploit these flaws to access unauthorized functionality and/or data, such as access other users’ accounts, view sensitive files, modify other users’ data, change access rights, etc. Security Misconfiguration. Security misconfiguration is the most commonly seen issue. This is commonly a result of insecure default configurations, incomplete or ad hoc configurations, open cloud storage, misconfigured HTTP headers, and verbose error messages containing sensitive information. Not only must all operating systems, frameworks, libraries, and applications be securely configured, but they must be patched/upgraded in a timely fashion. Cross-Site Scripting XSS. XSS flaws occur whenever an application includes untrusted data in a new web page without proper validation or escaping, or updates an existing web page with user-supplied data using a browser API that can create HTML or JavaScript. XSS allows attackers to execute scripts in the victim’s browser which can hijack user sessions, deface web sites, or redirect the user to malicious sites. Insecure Deserialization. Insecure deserialization often leads to remote code execution. Even if deserialization flaws do not result in remote code execution, they can be used to perform attacks, including replay attacks, injection attacks, and privilege escalation attacks. Using Components with Known Vulnerabilities. Components, such as libraries, frameworks, and other software modules, run with the same privileges as the application. If a vulnerable component is exploited, such an attack can facilitate serious data loss or server takeover. Applications and APIs using components with known vulnerabilities may undermine application defenses and enable various attacks and impacts. Insufficient Logging & Monitoring. Insufficient logging and monitoring, coupled with missing or ineffective integration with incident response, allows attackers to further attack systems, maintain persistence, pivot to more systems, and tamper, extract, or destroy data. Most breach studies show time to detect a breach is over 200 days, typically detected by external parties rather than internal processes or monitoring.

Data States and Data Remanence – Rest Motion or Transit