Cleartext logging of sensitive information

Attackers could gain access to sensitive information that is logged unencrypted.

Recommendation

Always make sure to encrypt or obfuscate sensitive information before you log it.

Generally, you should decrypt sensitive information only at the point where it is necessary for it to be used in cleartext.

Be aware that external processes often store the standard output and standard error streams of the application. This will include logged sensitive information.

Example

The following example code logs user credentials (in this case, their password) in plaintext:

let password = "P@ssw0rd"
NSLog("User password changed to \(password)")

Instead, you should encrypt or obfuscate the credentials, or omit them entirely:

let password = "P@ssw0rd"
NSLog("User password changed")

References

• M. Dowd, J. McDonald and J. Schuhm, The Art of Software Security Assessment, 1st Edition, Chapter 2 - 'Common Vulnerabilities of Encryption', p. 43. Addison Wesley, 2006.
• M. Howard and D. LeBlanc, Writing Secure Code, 2nd Edition, Chapter 9 - 'Protecting Secret Data', p. 299. Microsoft, 2002.
• OWASP: Logging Cheat Sheet.
• Common Weakness Enumeration: CWE-312.
• Common Weakness Enumeration: CWE-359.
• Common Weakness Enumeration: CWE-532.