CVE-2017-2624

It was found that xorg-x11-server before 1.19.0 including uses memcmp() to check the received MIT cookie against a series of valid cookies. If the cookie is correct, it is allowed to attach to the Xorg session. Since most memcmp() implementations return after an invalid byte is seen, this causes a time difference between a valid and invalid byte, which could allow an efficient brute force attack.

It was found that xorg-x11-server before 1.19.0 including uses memcmp() to check the received MIT cookie against a series of valid cookies. If the cookie is correct, it is allowed to attach to the Xorg session. Since most memcmp() implementations return after an invalid byte is seen, this causes a time difference between a valid and invalid byte, which could allow an efficient brute force attack.

Se ha encontrado que xorg-x11-server en versiones anteriores a la 1.19.0 que uttilizan memcmp() para comprobar la cookie MIT recibida contra una serie de cookies válidas. Si la cookie es correcta, se puede adjuntar a la sesión de Xorg. Dado que la mayoría de las implementaciones de memcmp() retornan después de que se identifique un byte no válido, esto provoca una diferencia de tiempo entre un byte válido y otro no válido, lo que podría permitir un ataque de fuerza bruta eficiente.