Scientific Linux Security Update : openssh on SL6.x i386/x86_64 (20120620)

#%NASL_MIN_LEVEL 70300
#
# (C) Tenable Network Security, Inc.
#
# The descriptive text is (C) Scientific Linux.
#

include('deprecated_nasl_level.inc');
include('compat.inc');

if (description)
{
  script_id(61345);
  script_version("1.6");
  script_set_attribute(attribute:"plugin_modification_date", value:"2021/01/14");

  script_cve_id("CVE-2011-5000");

  script_name(english:"Scientific Linux Security Update : openssh on SL6.x i386/x86_64 (20120620)");
  script_summary(english:"Checks rpm output for the updated packages");

  script_set_attribute(
    attribute:"synopsis", 
    value:
"The remote Scientific Linux host is missing one or more security
updates."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"OpenSSH is OpenBSD's Secure Shell (SSH) protocol implementation. These
packages include the core files necessary for the OpenSSH client and
server.

A denial of service flaw was found in the OpenSSH GSSAPI
authentication implementation. A remote, authenticated user could use
this flaw to make the OpenSSH server daemon (sshd) use an excessive
amount of memory, leading to a denial of service. GSSAPI
authentication is enabled by default ('GSSAPIAuthentication yes' in
'/etc/ssh/sshd_config'). (CVE-2011-5000)

These updated openssh packages also provide fixes for the following
bugs :

  - SSH X11 forwarding failed if IPv6 was enabled and the
    parameter X11UseLocalhost was set to 'no'. Consequently,
    users could not set X forwarding. This update fixes sshd
    and ssh to correctly bind the port for the IPv6
    protocol. As a result, X11 forwarding now works as
    expected with IPv6.

  - The sshd daemon was killed by the OOM killer when
    running a stress test. Consequently, a user could not
    log in. With this update, the sshd daemon sets its
    oom_adj value to -17. As a result, sshd is not chosen by
    OOM killer and users are able to log in to solve
    problems with memory.

  - If the SSH server is configured with a banner that
    contains a backslash character, then the client will
    escape it with another '\' character, so it prints
    double backslashes. An upstream patch has been applied
    to correct the problem and the SSH banner is now
    correctly displayed.

In addition, these updated openssh packages provide the following
enhancements :

  - Previously, SSH allowed multiple ways of authentication
    of which only one was required for a successful login.
    SSH can now be set up to require multiple ways of
    authentication. For example, logging in to an
    SSH-enabled machine requires both a passphrase and a
    public key to be entered. The RequiredAuthentications1
    and RequiredAuthentications2 options can be configured
    in the /etc/ssh/sshd_config file to specify
    authentications that are required for a successful
    login. For example, to set key and password
    authentication for SSH version 2, type :

echo 'RequiredAuthentications2 publickey,password' >>
/etc/ssh/sshd_config

For more information on the aforementioned /etc/ssh/sshd_config
options, refer to the sshd_config man page.

  - Previously, OpenSSH could use the Advanced Encryption
    Standard New Instructions (AES-NI) instruction set only
    with the AES Cipher-block chaining (CBC) cipher. This
    update adds support for Counter (CTR) mode encryption in
    OpenSSH so the AES-NI instruction set can now be used
    efficiently also with the AES CTR cipher.

  - Prior to this update, an unprivileged slave sshd process
    was run as the sshd_t context during privilege
    separation (privsep). sshd_t is the SELinux context used
    for running the sshd daemon. Given that the unprivileged
    slave process is run under the user's UID, it is fitting
    to run this process under the user's SELinux context
    instead of the privileged sshd_t context. With this
    update, the unprivileged slave process is now run as the
    user's context instead of the sshd_t context in
    accordance with the principle of privilege separation.
    The unprivileged process, which might be potentially
    more sensitive to security threats, is now run under the
    user's SELinux context.

Users are advised to upgrade to these updated openssh packages, which
contain backported patches to resolve these issues and add these
enhancements. After installing this update, the OpenSSH server daemon
(sshd) will be restarted automatically."
  );
  # https://listserv.fnal.gov/scripts/wa.exe?A2=ind1207&L=scientific-linux-errata&T=0&P=2301
  script_set_attribute(
    attribute:"see_also",
    value:"http://www.nessus.org/u?724debbd"
  );
  script_set_attribute(attribute:"solution", value:"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:S/C:N/I:N/A:P");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fermilab:scientific_linux:openssh");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fermilab:scientific_linux:openssh-askpass");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fermilab:scientific_linux:openssh-clients");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fermilab:scientific_linux:openssh-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fermilab:scientific_linux:openssh-ldap");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fermilab:scientific_linux:openssh-server");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fermilab:scientific_linux:pam_ssh_agent_auth");
  script_set_attribute(attribute:"cpe", value:"x-cpe:/o:fermilab:scientific_linux");

  script_set_attribute(attribute:"vuln_publication_date", value:"2012/04/05");
  script_set_attribute(attribute:"patch_publication_date", value:"2012/06/20");
  script_set_attribute(attribute:"plugin_publication_date", value:"2012/08/01");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2012-2021 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"Scientific Linux Local Security Checks");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/cpu", "Host/RedHat/release", "Host/RedHat/rpm-list");

  exit(0);
}


include("audit.inc");
include("global_settings.inc");
include("misc_func.inc");
include("rpm.inc");

if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
release = get_kb_item("Host/RedHat/release");
if (isnull(release) || "Scientific Linux " >!< release) audit(AUDIT_HOST_NOT, "running Scientific Linux");
os_ver = pregmatch(pattern: "Scientific Linux.*release ([0-9]+(\.[0-9]+)?)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Scientific Linux");
os_ver = os_ver[1];
if (! preg(pattern:"^6([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, "Scientific Linux 6.x", "Scientific Linux " + os_ver);
if (!get_kb_item("Host/RedHat/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);

cpu = get_kb_item("Host/cpu");
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if (cpu >!< "x86_64" && cpu !~ "^i[3-6]86$") audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "Scientific Linux", cpu);


flag = 0;
if (rpm_check(release:"SL6", reference:"openssh-5.3p1-81.el6")) flag++;
if (rpm_check(release:"SL6", reference:"openssh-askpass-5.3p1-81.el6")) flag++;
if (rpm_check(release:"SL6", reference:"openssh-clients-5.3p1-81.el6")) flag++;
if (rpm_check(release:"SL6", reference:"openssh-debuginfo-5.3p1-81.el6")) flag++;
if (rpm_check(release:"SL6", reference:"openssh-ldap-5.3p1-81.el6")) flag++;
if (rpm_check(release:"SL6", reference:"openssh-server-5.3p1-81.el6")) flag++;
if (rpm_check(release:"SL6", reference:"pam_ssh_agent_auth-0.9-81.el6")) flag++;


if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_NOTE,
    extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "openssh / openssh-askpass / openssh-clients / openssh-debuginfo / etc");
}