CVE-2020-15023

Askey AP5100W devices through AP5100W_Dual_SIG_1.01.097 are affected by WPS PIN offline brute-force cracking. This arises because of issues with the random number selection for the Diffie-Hellman exchange. By capturing an attempted (and even failed) WPS authentication attempt, it is possible to brute force the overall authentication exchange. This allows an attacker to obtain the recovered WPS PIN in minutes or even seconds, and eventually obtain the Wi-Fi PSK key, gaining access to the Wi=Fi network.

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://medium.com/csg-govtech/bolstering-security-how-i-breached-a-wifi-mesh-access-point-from-close-proximity-to-uncover-f8f77dc3cd5d
• https://www.askey.com.tw/Products/wifi.html
• https://www.askey.com.tw/incident_report_notifications.html