CVE-2015-5600

The kbdint_next_device function in auth2-chall.c in sshd in OpenSSH through 6.9 does not properly restrict the processing of keyboard-interactive devices within a single connection, which makes it easier for remote attackers to conduct brute-force attacks or cause a denial of service (CPU consumption) via a long and duplicative list in the ssh -oKbdInteractiveDevices option, as demonstrated by a modified client that provides a different password for each pam element on this list.

The OpenSSH server, when keyboard-interactive challenge response authentication is enabled and PAM is being used (the default configuration in Mageia), can be tricked into allowing more password attempts than the MaxAuthTries setting would normally allow in one connection, which can aid an attacker in brute-force password guessing (CVE-2015-5600).

openssh was updated to fix several security issues.

These security issues were fixed:

• CVE-2015-5352: The x11_open_helper function in channels.c in ssh in OpenSSH when ForwardX11Trusted mode is not used, lacked a check of the refusal deadline for X connections, which made it easier for remote attackers to bypass intended access restrictions via a connection outside of the permitted time window (bsc#936695).
• CVE-2015-5600: The kbdint_next_device function in auth2-chall.c in sshd in OpenSSH did not properly restrict the processing of keyboard-interactive devices within a single connection, which made it easier for remote attackers to conduct brute-force attacks or cause a denial of service (CPU consumption) via a long and duplicative list in the ssh -oKbdInteractiveDevices option, as demonstrated by a modified client that provides a different password for each pam element on this list (bsc#938746).
• CVE-2015-4000: Removed and disabled weak DH groups to address LOGJAM (bsc#932483).
• Hardening patch to fix sftp RCE (bsc#903649).
• CVE-2015-6563: The monitor component in sshd in OpenSSH accepted extraneous username data in MONITOR_REQ_PAM_INIT_CTX requests, which allowed local users to conduct impersonation attacks by leveraging any SSH login access in conjunction with control of the sshd uid to send a crafted MONITOR_REQ_PWNAM request, related to monitor.c and monitor_wrap.c. (bsc#943010)
• CVE-2015-6564: Use-after-free vulnerability in the mm_answer_pam_free_ctx function in monitor.c in sshd in OpenSSH might have allowed local users to gain privileges by leveraging control of the sshd uid to send an unexpectedly early MONITOR_REQ_PAM_FREE_CTX request. (bsc#943006)

Also use %restart_on_update in the trigger script.

openssh was updated to fix several security issues and bugs.

These security issues were fixed:

• CVE-2015-5352: The x11_open_helper function in channels.c in ssh in OpenSSH when ForwardX11Trusted mode is not used, lacked a check of the refusal deadline for X connections, which made it easier for remote attackers to bypass intended access restrictions via a connection outside of the permitted time window (bsc#936695).
• CVE-2015-5600: The kbdint_next_device function in auth2-chall.c in sshd in OpenSSH did not properly restrict the processing of keyboard-interactive devices within a single connection, which made it easier for remote attackers to conduct brute-force attacks or cause a denial of service (CPU consumption) via a long and duplicative list in the ssh -oKbdInteractiveDevices option, as demonstrated by a modified client that provides a different password for each pam element on this list (bsc#938746).
• CVE-2015-4000: Removed and disabled weak DH groups to address LOGJAM (bsc#932483).
• Hardening patch to fix sftp RCE (bsc#903649).
• CVE-2015-6563: The monitor component in sshd in OpenSSH accepted extraneous username data in MONITOR_REQ_PAM_INIT_CTX requests, which allowed local users to conduct impersonation attacks by leveraging any SSH login access in conjunction with control of the sshd uid to send a crafted MONITOR_REQ_PWNAM request, related to monitor.c and monitor_wrap.c.
• CVE-2015-6564: Use-after-free vulnerability in the mm_answer_pam_free_ctx function in monitor.c in sshd in OpenSSH might have allowed local users to gain privileges by leveraging control of the sshd uid to send an unexpectedly early MONITOR_REQ_PAM_FREE_CTX request.

These non-security issues were fixed:

• bsc#914309: sshd inherits oom_adj -17 on SIGHUP causing DoS potential for oom_killer.
• bsc#673532: limits.conf fsize change in SLES10SP3 causing problems to WebSphere mqm user.
• bsc#916549: Fixed support for [email protected].

OpenSSH was updated to fix several security issues and bugs.

Please note that due to a bug in the previous shipped openssh version, sshd might not correctly restart. Please verify that the ssh daemon is running after installing this update.

These security issues were fixed:

• CVE-2015-5352: The x11_open_helper function, when ForwardX11Trusted mode is not used, lacked a check of the refusal deadline for X connections, which made it easier for remote attackers to bypass intended access restrictions via a connection outside of the permitted time window. (bsc#936695)

• CVE-2015-5600: The kbdint_next_device function in auth2-chall.c in sshd did not properly restrict the processing of keyboard-interactive devices within a single connection, which made it easier for remote attackers to conduct brute-force attacks or cause a denial of service (CPU consumption) via a long and duplicative list in the ssh -oKbdInteractiveDevices option, as demonstrated by a modified client that provides a different password for each pam element on this list. (bsc#938746)

• CVE-2015-4000: Removed and disabled weak DH groups to address LOGJAM. (bsc#932483)

• Hardening patch to fix sftp RCE. (bsc#903649)

• CVE-2015-6563: The monitor component in sshd accepted extraneous username data in MONITOR_REQ_PAM_INIT_CTX requests, which allowed local users to conduct impersonation attacks by leveraging any SSH login access in conjunction with control of the sshd uid to send a crafted MONITOR_REQ_PWNAM request, related to monitor.c and monitor_wrap.c.

• CVE-2015-6564: Use-after-free vulnerability in the mm_answer_pam_free_ctx function in monitor.c in sshd might have allowed local users to gain privileges by leveraging control of the sshd uid to send an unexpectedly early MONITOR_REQ_PAM_FREE_CTX request.

Additional a bug was fixed that could lead to openssh not working in chroot (bsc#947458).

openssh was updated to fix four security issues.

These security issues were fixed:

• CVE-2015-5352: The x11_open_helper function in channels.c in ssh in OpenSSH when ForwardX11Trusted mode is not used, lacked a check of the refusal deadline for X connections, which made it easier for remote attackers to bypass intended access restrictions via a connection outside of the permitted time window (bsc#936695).
• CVE-2015-5600: The kbdint_next_device function in auth2-chall.c in sshd in OpenSSH did not properly restrict the processing of keyboard-interactive devices within a single connection, which made it easier for remote attackers to conduct brute-force attacks or cause a denial of service (CPU consumption) via a long and duplicative list in the ssh -oKbdInteractiveDevices option, as demonstrated by a modified client that provides a different password for each pam element on this list (bsc#938746).
• CVE-2015-4000: Removed and disabled weak DH groups (bsc#932483).
• Hardening patch to fix sftp RCE (bsc#903649).

These non-security issues were fixed:

• bsc#914309: sshd inherits oom_adj -17 on SIGHUP causing DoS potential for oom_killer.
• bsc#673532: limits.conf fsize change in SLES10SP3 causing problems to WebSphere mqm user.

Moritz Jodeit discovered that OpenSSH incorrectly handled usernames when using PAM authentication. If an additional vulnerability were discovered in the OpenSSH unprivileged child process, this issue could allow a remote attacker to perform user impersonation. (CVE number pending)

Moritz Jodeit discovered that OpenSSH incorrectly handled context memory when using PAM authentication. If an additional vulnerability were discovered in the OpenSSH unprivileged child process, this issue could allow a remote attacker to bypass authentication or possibly execute arbitrary code. (CVE number pending)

Jann Horn discovered that OpenSSH incorrectly handled time windows for X connections. A remote attacker could use this issue to bypass certain access restrictions. (CVE-2015-5352)

It was discovered that OpenSSH incorrectly handled keyboard-interactive authentication. In a non-default configuration, a remote attacker could possibly use this issue to perform a brute-force password attack. (CVE-2015-5600)