CVE-2020-8792

The OKLOK (3.1.1) mobile companion app for Fingerprint Bluetooth Padlock FB50 (2.3) has an information-exposure issue. In the mobile app, an attempt to add an already-bound lock by its barcode reveals the email address of the account to which the lock is bound, as well as the name of the lock. Valid barcode inputs can be easily guessed because barcode strings follow a predictable pattern. Correctly guessed valid barcode inputs entered through the app interface disclose arbitrary users email addresses and lock names.

Weakness

The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers.

Affected Software

Potential Mitigations

• Use a well-vetted algorithm that is currently considered to be strong by experts in the field, and select well-tested implementations with adequate length seeds.
• In general, if a pseudo-random number generator is not advertised as being cryptographically secure, then it is probably a statistical PRNG and should not be used in security-sensitive contexts.
• Pseudo-random number generators can produce predictable numbers if the generator is known and the seed can be guessed. A 256-bit seed is a good starting point for producing a “random enough” number.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/112.html
• https://cwe.mitre.org/data/definitions/485.html
• https://cwe.mitre.org/data/definitions/59.html

References

• https://github.com/fierceoj/ownklok