Updated openssh packages that fix an authentication flaw are now available for Red Hat Enterprise Linux 3 and 4.

This update has been rated as having low security impact by the Red Hat Security Response Team.

OpenSSH is OpenBSD's SSH (Secure SHell) protocol implementation. This package includes the core files necessary for both the OpenSSH client and server.

An authentication flaw was found in OpenSSH's privilege separation monitor. If it ever becomes possible to alter the behavior of the unprivileged process when OpenSSH is using privilege separation, an attacker may then be able to login without possessing proper credentials. (CVE-2006-5794)

Please note that this flaw by itself poses no direct threat to OpenSSH users. Without another security flaw that could allow an attacker to alter the behavior of OpenSSH's unprivileged process, this flaw cannot be exploited. There are currently no known flaws to exploit this behavior. However, we have decided to issue this erratum to fix this flaw to reduce the security impact if an unprivileged process flaw is ever found.

Users of openssh should upgrade to these updated packages, which contain a backported patch to resolve this issue.

The version of SunSSH running on the remote host has an information disclosure vulnerability.  A design flaw in the SSH specification could allow a man-in-the-middle attacker to recover up to 32 bits of plaintext from an SSH-protected connection in the standard configuration.  An attacker could exploit this to gain access to sensitive information.

Note that this version of SunSSH is also prone to several additional issues but Nessus did not test for them.

According to its banner, the remote host is running a version of OpenSSH prior to 4.5.  Versions before 4.5 are affected by the following vulnerabilities :

  - A client-side NULL pointer dereference, caused by a     protocol error from a malicious server, which could     cause the client to crash. (CVE-2006-4925)

  - A privilege separation vulnerability exists, which could     allow attackers to bypass authentication. The     vulnerability is caused by a design error between     privileged processes and their child processes. Note     that this particular issue is only exploitable when     other vulnerabilities are present. (CVE-2006-5794)

  - An attacker that connects to the service before it has     finished creating keys could force the keys to be     recreated. This could result in a denial of service for     any processes that relies on a trust relationship with     the server. Note that this particular issue only affects     the Apple implementation of OpenSSH on Mac OS X.     (CVE-2007-0726)

The remote NewStart CGSL host, running version CORE 5.04 / MAIN 5.04, has openssh packages installed that are affected by multiple vulnerabilities:

  - scp in OpenSSH 4.2p1 allows attackers to execute     arbitrary commands via filenames that contain shell     metacharacters or spaces, which are expanded twice.
    (CVE-2006-0225)

  - sshd in OpenSSH before 4.4, when using the version 1 SSH     protocol, allows remote attackers to cause a denial of     service (CPU consumption) via an SSH packet that     contains duplicate blocks, which is not properly handled     by the CRC compensation attack detector. (CVE-2006-4924)

  - Signal handler race condition in OpenSSH before 4.4     allows remote attackers to cause a denial of service     (crash), and possibly execute arbitrary code if GSSAPI     authentication is enabled, via unspecified vectors that     lead to a double-free. (CVE-2006-5051)

  - Unspecified vulnerability in the sshd Privilege     Separation Monitor in OpenSSH before 4.5 causes weaker     verification that authentication has been successful,     which might allow attackers to bypass authentication.
    NOTE: as of 20061108, it is believed that this issue is     only exploitable by leveraging vulnerabilities in the     unprivileged process, which are not known to exist.
    (CVE-2006-5794)

  - Unspecified vulnerability in the     linux_audit_record_event function in OpenSSH 4.3p2, as     used on Fedora Core 6 and possibly other systems, allows     remote attackers to write arbitrary characters to an     audit log via a crafted username. NOTE: some of these     details are obtained from third party information.
    (CVE-2007-3102)

  - The (1) remote_glob function in sftp-glob.c and the (2)     process_put function in sftp.c in OpenSSH 5.8 and     earlier, as used in FreeBSD 7.3 and 8.1, NetBSD 5.0.2,     OpenBSD 4.7, and other products, allow remote     authenticated users to cause a denial of service (CPU     and memory consumption) via crafted glob expressions     that do not match any pathnames, as demonstrated by glob     expressions in SSH_FXP_STAT requests to an sftp daemon,     a different vulnerability than CVE-2010-2632.
    (CVE-2010-4755)

  - The default configuration of OpenSSH through 6.1     enforces a fixed time limit between establishing a TCP     connection and completing a login, which makes it easier     for remote attackers to cause a denial of service     (connection-slot exhaustion) by periodically making many     new TCP connections. (CVE-2010-5107)

  - It was found that OpenSSH did not properly handle     certain AcceptEnv parameter values with wildcard     characters. A remote attacker could use this flaw to     bypass intended environment variable restrictions.
    (CVE-2014-2532)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The OpenSSH release 4.5 contains a security fix which has been backported to the openssh versions in our old products.

CVE-2006-5794: Incorrect return argument checking in the privilege separation monitor was fixed. In case of an exploitable unprivileged helper this could have been used to elevate privileges.

From Red Hat Security Advisory 2006:0738 :

Updated openssh packages that fix an authentication flaw are now available for Red Hat Enterprise Linux 3 and 4.

This update has been rated as having low security impact by the Red Hat Security Response Team.

OpenSSH is OpenBSD's SSH (Secure SHell) protocol implementation. This package includes the core files necessary for both the OpenSSH client and server.

An authentication flaw was found in OpenSSH's privilege separation monitor. If it ever becomes possible to alter the behavior of the unprivileged process when OpenSSH is using privilege separation, an attacker may then be able to login without possessing proper credentials. (CVE-2006-5794)

Please note that this flaw by itself poses no direct threat to OpenSSH users. Without another security flaw that could allow an attacker to alter the behavior of OpenSSH's unprivileged process, this flaw cannot be exploited. There are currently no known flaws to exploit this behavior. However, we have decided to issue this erratum to fix this flaw to reduce the security impact if an unprivileged process flaw is ever found.

Users of openssh should upgrade to these updated packages, which contain a backported patch to resolve this issue.

The remote NewStart CGSL host, running version MAIN 4.05, has openssh-latest packages installed that are affected by multiple vulnerabilities:

  - scp in OpenSSH 4.2p1 allows attackers to execute     arbitrary commands via filenames that contain shell     metacharacters or spaces, which are expanded twice.
    (CVE-2006-0225)

  - sshd in OpenSSH before 4.4, when using the version 1 SSH     protocol, allows remote attackers to cause a denial of     service (CPU consumption) via an SSH packet that     contains duplicate blocks, which is not properly handled     by the CRC compensation attack detector. (CVE-2006-4924)

  - Signal handler race condition in OpenSSH before 4.4     allows remote attackers to cause a denial of service     (crash), and possibly execute arbitrary code if GSSAPI     authentication is enabled, via unspecified vectors that     lead to a double-free. (CVE-2006-5051)

  - Unspecified vulnerability in the sshd Privilege     Separation Monitor in OpenSSH before 4.5 causes weaker     verification that authentication has been successful,     which might allow attackers to bypass authentication.
    NOTE: as of 20061108, it is believed that this issue is     only exploitable by leveraging vulnerabilities in the     unprivileged process, which are not known to exist.
    (CVE-2006-5794)

  - Unspecified vulnerability in the     linux_audit_record_event function in OpenSSH 4.3p2, as     used on Fedora Core 6 and possibly other systems, allows     remote attackers to write arbitrary characters to an     audit log via a crafted username. NOTE: some of these     details are obtained from third party information.
    (CVE-2007-3102)

  - The (1) remote_glob function in sftp-glob.c and the (2)     process_put function in sftp.c in OpenSSH 5.8 and     earlier, as used in FreeBSD 7.3 and 8.1, NetBSD 5.0.2,     OpenBSD 4.7, and other products, allow remote     authenticated users to cause a denial of service (CPU     and memory consumption) via crafted glob expressions     that do not match any pathnames, as demonstrated by glob     expressions in SSH_FXP_STAT requests to an sftp daemon,     a different vulnerability than CVE-2010-2632.
    (CVE-2010-4755)

  - The default configuration of OpenSSH through 6.1     enforces a fixed time limit between establishing a TCP     connection and completing a login, which makes it easier     for remote attackers to cause a denial of service     (connection-slot exhaustion) by periodically making many     new TCP connections. (CVE-2010-5107)

  - It was found that OpenSSH did not properly handle     certain AcceptEnv parameter values with wildcard     characters. A remote attacker could use this flaw to     bypass intended environment variable restrictions.
    (CVE-2014-2532)

  - It was discovered that OpenSSH clients did not correctly     verify DNS SSHFP records. A malicious server could use     this flaw to force a connecting client to skip the DNS     SSHFP record check and require the user to perform     manual host verification of the DNS SSHFP record.
    (CVE-2014-2653)

  - It was found that when OpenSSH was used in a Kerberos     environment, remote authenticated users were allowed to     log in as a different user if they were listed in the     ~/.k5users file of that user, potentially bypassing     intended authentication restrictions. (CVE-2014-9278)

  - It was discovered that the OpenSSH sshd daemon did not     check the list of keyboard-interactive authentication     methods for duplicates. A remote attacker could use this     flaw to bypass the MaxAuthTries limit, making it easier     to perform password guessing attacks. (CVE-2015-5600)

  - It was discovered that the OpenSSH sshd daemon fetched     PAM environment settings before running the login     program. In configurations with UseLogin=yes and the     pam_env PAM module configured to read user environment     settings, a local user could use this flaw to execute     arbitrary code as root. (CVE-2015-8325)

  - An information leak flaw was found in the way the     OpenSSH client roaming feature was implemented. A     malicious server could potentially use this flaw to leak     portions of memory (possibly including private SSH keys)     of a successfully authenticated OpenSSH client.
    (CVE-2016-0777)

  - An access flaw was discovered in OpenSSH; the OpenSSH     client did not correctly handle failures to generate     authentication cookies for untrusted X11 forwarding. A     malicious or compromised remote X application could     possibly use this flaw to establish a trusted connection     to the local X server, even if only untrusted X11     forwarding was requested. (CVE-2016-1908)

  - A covert timing channel flaw was found in the way     OpenSSH handled authentication of non-existent users. A     remote unauthenticated attacker could possibly use this     flaw to determine valid user names by measuring the     timing of server responses. (CVE-2016-6210)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

A vulnerability in the privilege separation functionality in OpenSSH was discovered, caused by an incorrect checking for bad signatures in sshd's privsep monitor. As a result, the monitor and the unprivileged process can get out sync. The OpenSSH team indicated that this bug is not known to be exploitable in the abence of additional vulnerabilities.

Updated packages have been patched to correct this issue, and Mandriva Linux 2007 has received the latest version of OpenSSH.

The OpenSSH release 4.5 contains a security fix which has been backported to the openssh versions in our old products.

  - Incorrect return argument checking in the privilege     separation monitor was fixed. In case of an exploitable     unprivileged helper this could have been used to elevate     privileges. (CVE-2006-5794)

The installed version of OpenSSH is prior to 4.5 and is affected by the following vulnerabilities:

 - A client-side NULL pointer dereference, caused by a protocol error from a malicious server, which could cause the client to crash. (CVE-2006-4925)
 - A privilege separation vulnerability exists, which could allow attackers to bypass authentication. The vulnerability is caused by a design error between privileged processes and their child processes. Note that this particular issue is only exploitable when other vulnerabilities are present. (CVE-2006-5794)
 - An attacker that connects to the service before it has finished creating keys could force the keys to be recreated. This could result in a denial of service for any processes that relies on a trust relationship with the server. Note that this particular issue only affects the Apple implementation of OpenSSH on Mac OS X. (CVE-2007-0726)

ID	Name	Product	Family	Published	Updated	Severity
37366	CentOS 3 / 4 : openssh (CESA-2006:0738)	Nessus	CentOS Local Security Checks	4/23/2009	1/4/2021	high
55992	SunSSH < 1.1.1 / 1.3 CBC Plaintext Disclosure	Nessus	Misc.	8/29/2011	9/21/2020	critical
44077	OpenSSH < 4.5 Multiple Vulnerabilities	Nessus	Misc.	10/4/2011	3/27/2024	high
23683	RHEL 3 / 4 : openssh (RHSA-2006:0738)	Nessus	Red Hat Local Security Checks	11/20/2006	1/14/2021	high
127206	NewStart CGSL CORE 5.04 / MAIN 5.04 : openssh Multiple Vulnerabilities (NS-SA-2019-0036)	Nessus	NewStart CGSL Local Security Checks	8/12/2019	5/8/2024	high
27366	openSUSE 10 Security Update : openssh (openssh-2256)	Nessus	SuSE Local Security Checks	10/17/2007	1/14/2021	high
67425	Oracle Linux 3 / 4 : openssh (ELSA-2006-0738)	Nessus	Oracle Linux Local Security Checks	7/12/2013	1/14/2021	high
127415	NewStart CGSL MAIN 4.05 : openssh-latest Multiple Vulnerabilities (NS-SA-2019-0146)	Nessus	NewStart CGSL Local Security Checks	8/12/2019	5/19/2022	critical
24589	Mandrake Linux Security Advisory : openssh (MDKSA-2006:204)	Nessus	Mandriva Local Security Checks	2/18/2007	1/6/2021	high
29539	SuSE 10 Security Update : OpenSSH (ZYPP Patch Number 2257)	Nessus	SuSE Local Security Checks	12/13/2007	1/14/2021	high
701165	OpenSSH < 4.5 Multiple Vulnerabilities	Nessus Network Monitor	SSH	8/21/2019	8/21/2019	high

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