CVE-2019-12821

A vulnerability was found in the app 2.0 of the Shenzhen Jisiwei i3 robot vacuum cleaner, while adding a device to the account using a QR-code. The QR-code follows an easily predictable pattern that depends only on the specific device ID of the robot vacuum cleaner. By generating a QR-code containing information about the device ID, it is possible to connect an arbitrary device and gain full access to it. The device ID has an initial JSW substring followed by a six digit number that depends on the specific device.

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://www.kth.se/polopoly_fs/1.914058.1561621210%21/Olsson_Larsson-Forsberg_vacuum.pdf