Here we discuss some sensitive data exposure remediations, which will help you to protect one of the OWASP top 10 vulnerabilities, lets start with first some introduction.
What is sensitive data exposure?
Sensitive Data Exposure occurs when an application does not adequately protect sensitive information. The data can vary and anything from passwords, session tokens, credit card data to private health data and more can be exposed.
A few examples would be exposed data that someone mistakenly uploaded somewhere, weak crypto that means an attacker would be able to read the data if they successfully compromised the target and the lack of headers that prevent browser caching. In short, every possible way where it would have been possible to better protect the sensitive data.
Weakness and Impact of not using sensitive data exposure remediation
Over the last few years, this has been the most common impactful attack. The most common flaw is simply not encrypting sensitive data. When crypto is employed, weak key generation and management, and weak algorithm, protocol, and cipher usage are common, particularly for weak password hashing storage techniques. For data in transit, server-side weaknesses are mainly easy to detect, but hard for data at rest.
Failure frequently compromises all data that should have been protected. Typically, this information includes sensitive personal information (PII) data such as health records, credentials, personal data, and credit cards, which often require protection as defined by laws or regulations such as the EU GDPR or local privacy laws.
How to verify your application for this vulnerability?
The first thing is to determine the protection needs of data in transit and at rest. For example, passwords, credit card numbers, health records, personal information, and business secrets require extra protection, particularly if that data falls under privacy laws, e.g. EU’s General Data Protection Regulation (GDPR), or regulations, e.g. financial data protection such as PCI Data Security Standard (PCI DSS). For all such data:
- Is any data transmitted in clear text? This concern protocols such as HTTP, SMTP, and FTP. External internet traffic is especially dangerous. Verify all internal traffic e.g. between load balancers, web servers, or back-end systems.
- Are any old or weak cryptographic algorithms used either by default or in older code?
- Are default crypto keys in use, weak crypto keys generated, or re-used, or is proper key management or rotation missing?
- Is encryption not enforced, e.g. are any user agent (browser) security directives or headers missing?
- Does the user agent (e.g. app, mail client) not verify if the received server certificate is valid?
Attack scenario for vulnerability
Before moving towards sensitive data exposure remediations let see some example attack scenarios:
Scenario #1: An application encrypts credit card numbers in a database using automatic database encryption. However, this data is automatically decrypted when retrieved, allowing a SQL injection flaw to retrieve credit card numbers in cleartext.
Scenario #2: A site doesn’t use or enforce TLS for all pages or supports weak encryption. An attacker monitors network traffic (e.g. at an insecure wireless network), downgrades connections from HTTPS to HTTP, intercepts requests, and steals the user’s session cookie.
The attacker then replays this cookie and hijacks the user’s (authenticated) session, accessing or modifying the user’s private data. Instead of the above, they could alter all transported data, e.g. the recipient of a money transfer.
Scenario #3: The password database uses unsalted or simple hashes to store everyone’s passwords. A file upload flaw allows an attacker to retrieve the password database. All the unsalted hashes can be exposed with a rainbow table of pre-calculated hashes. Hashes generated by simple or fast hash functions may be cracked by GPUs, even if they were salted.
9 sensitive data exposure remediations
Here are some sensitive data exposure remediations, so do the following, at a minimum, and consult the references:
- Classify data processed, stored, or transmitted by an application. Identify which data is sensitive according to privacy laws, regulatory requirements, or business needs.
- Apply controls as per the classification.
- Don’t store sensitive data unnecessarily. Discard it as soon as possible or use PCI DSS compliant tokenization or even truncation. Data that is not retained cannot be stolen.
- Make sure to encrypt all sensitive data at rest.
- Ensure up-to-date and strong standard algorithms, protocols, and keys are in place; use proper key management.
- Encrypt all data in transit with security protocols such as TLS with perfect forward secrecy (PFS) ciphers, cipher prioritization by the server, and security parameters. Enforce encryption using directives like HTTP Strict Transport Security (HSTS).
- Disable caching for responses that contain sensitive data.
- Store passwords using strong adaptive and salted hashing functions with a work factor (delay factor), such as Argon2, scrypt, bcrypt or PBKDF2.
- Verify independently the effectiveness of configuration and settings.
Following sensitive data exposure remediations are not very tough, we just need some regular attention during the development process and in testing