Keamanan
OpenSSH is developed with the same rigorous security process that the
OpenBSD group is famous for.
For more information, see the
OpenBSD Security page.
- OpenSSH was not vulnerable to the RC4 cipher
password cracking,
replay, or
modification
attacks. At the time that OpenSSH was started, it was already known
that SSH 1 used the RC4 stream cipher completely incorrectly, and
thus RC4 support was removed.
- OpenSSH was not vulnerable to
client forwarding attacks
in unencrypted connections, since unencrypted connection support was
removed at OpenSSH project start.
- OpenSSH was not vulnerable to IDEA-encryption algorithm
attacks on the last packet,
since the IDEA algorithm is not supported. The patent status of IDEA makes
it unsuitable for inclusion in OpenSSH.
- OpenSSH does not treat localhost as exempt from host key checking,
thus making it not vulnerable to the
host key authentication bypass
attack.
- OpenSSH was not vulnerable to
uncontrollable X11 forwarding
attacks because X11-forwarding is disabled by default and the user can
de-permit it.
- OpenSSH has the SSH 1 protocol deficiency that might make an insertion attack
difficult but possible. The CORE-SDI
deattack mechanism
is used to eliminate
the common case. Ways of solving this problem are being investigated, since
the SSH 1 protocol is not dead yet.
- OpenSSH was never vulnerable to the
"Feb 5, 2001: SSH-1 Brute Force Password Vulnerability",
Crimelabs Security Note CLABS200101.
- OpenSSH 2.1.0 and newer do not allow a remote attacker to
execute arbitrary commands with the privileges of sshd if UseLogin
is enabled by the administrator. UseLogin is disabled by default.
This problem has been fixed in OpenSSH 2.1.0.
- OpenSSH 2.2.0 and newer are not vulnerable to the
"Feb 7, 2001: SSH-1 Session Key Recovery Vulnerability",
CORE-SDI Advisory CORE-20010116. OpenSSH imposes limits on the
connection rate, making the attack unfeasible. Additionally, the
Bleichenbacher oracle has been closed completely since January 29,
2001.
- OpenSSH 2.3.0 and newer are not vulnerable to the
"Feb 8, 2001: SSH-1 Daemon CRC32 Compensation Attack Detector Vulnerability",
RAZOR Bindview Advisory CAN-2001-0144.
A buffer overflow in the CRC32 compensation attack detector can
lead to remote root access. This problem has been fixed in
OpenSSH 2.3.0. However, versions prior to 2.3.0 are vulnerable.
- OpenSSH 2.3.0 and newer do not allow
malicious servers to access the client's X11 display or ssh-agent.
This problem has been fixed in OpenSSH 2.3.0.
- OpenSSH 2.3.1, a development snapshot which was never released, was
vulnerable to
"Feb 8, 2001: Authentication By-Pass Vulnerability in OpenSSH-2.3.1",
OpenBSD Security Advisory.
In protocol 2, authentication could be bypassed if public key
authentication was permitted. This problem does exist only
in OpenSSH 2.3.1, a three week internal development release.
OpenSSH 2.3.0 and versions newer than 2.3.1 are not vulnerable to
this problem.
- OpenSSH 2.9.9 and newer do not
allow users to
delete files named "cookies" if X11 forwarding is enabled.
X11 forwarding is disabled by default.
- OpenSSH 2.9.9 and newer are not vulnerable to
"Sep 26, 2001: Weakness in OpenSSH's source IP based access control
for SSH protocol v2 public key authentication.",
OpenSSH Security Advisory.
- OpenSSH 3.0.2 and newer do not
allow users to
pass environment variables to login(1) if UseLogin is enabled.
The UseLogin option is disabled by default in all OpenSSH releases.
- OpenSSH 3.1 and newer are not vulnerable to
"March 7, 2002: Off-by-one error in the channel code",
OpenSSH
Security Advisory.
- OpenSSH 3.2.1 and newer are not vulnerable to
"April 21, 2002: Buffer overflow in AFS/Kerberos token passing code",
OpenSSH
Security Advisory:
Versions prior to OpenSSH 3.2.1 allow privileged access if
AFS/Kerberos token passing is compiled in and enabled (either
in the system or in sshd_config).
- OpenSSH 3.4 and newer are not vulnerable to
"June 26, 2002: OpenSSH Remote Challenge Vulnerability",
OpenSSH
Security Advisory.
www@openbsd.org
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