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nessusThis script is Copyright (C) 2016-2021 and is owned by Tenable, Inc. or an Affiliate thereof.DEBIAN_DSA-3626.NASL
HistoryJul 25, 2016 - 12:00 a.m.

Debian DSA-3626-1 : openssh - security update

2016-07-2500:00:00
This script is Copyright (C) 2016-2021 and is owned by Tenable, Inc. or an Affiliate thereof.
www.tenable.com
36

Eddie Harari reported that the OpenSSH SSH daemon allows user enumeration through timing differences when trying to authenticate users. When sshd tries to authenticate a non-existing user, it will pick up a fixed fake password structure with a hash based on the Blowfish algorithm. If real users passwords are hashed using SHA256/SHA512, then a remote attacker can take advantage of this flaw by sending large passwords, receiving shorter response times from the server for non-existing users.

#%NASL_MIN_LEVEL 70300
#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were  
# extracted from Debian Security Advisory DSA-3626. The text 
# itself is copyright (C) Software in the Public Interest, Inc.
#

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

if (description)
{
  script_id(92526);
  script_version("2.9");
  script_set_attribute(attribute:"plugin_modification_date", value:"2021/01/11");

  script_cve_id("CVE-2016-6210");
  script_xref(name:"DSA", value:"3626");

  script_name(english:"Debian DSA-3626-1 : openssh - security update");
  script_summary(english:"Checks dpkg output for the updated package");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote Debian host is missing a security-related update."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"Eddie Harari reported that the OpenSSH SSH daemon allows user
enumeration through timing differences when trying to authenticate
users. When sshd tries to authenticate a non-existing user, it will
pick up a fixed fake password structure with a hash based on the
Blowfish algorithm. If real users passwords are hashed using
SHA256/SHA512, then a remote attacker can take advantage of this flaw
by sending large passwords, receiving shorter response times from the
server for non-existing users."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=831902"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://packages.debian.org/source/jessie/openssh"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://www.debian.org/security/2016/dsa-3626"
  );
  script_set_attribute(
    attribute:"solution", 
    value:
"Upgrade the openssh packages.

For the stable distribution (jessie), this problem has been fixed in
version 1:6.7p1-5+deb8u3."
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:P/I:N/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:openssh");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:8.0");

  script_set_attribute(attribute:"patch_publication_date", value:"2016/07/24");
  script_set_attribute(attribute:"plugin_publication_date", value:"2016/07/25");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2016-2021 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"Debian Local Security Checks");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/Debian/release", "Host/Debian/dpkg-l");

  exit(0);
}


include("audit.inc");
include("debian_package.inc");


if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (!get_kb_item("Host/Debian/release")) audit(AUDIT_OS_NOT, "Debian");
if (!get_kb_item("Host/Debian/dpkg-l")) audit(AUDIT_PACKAGE_LIST_MISSING);


flag = 0;
if (deb_check(release:"8.0", prefix:"openssh-client", reference:"1:6.7p1-5+deb8u3")) flag++;
if (deb_check(release:"8.0", prefix:"openssh-client-udeb", reference:"1:6.7p1-5+deb8u3")) flag++;
if (deb_check(release:"8.0", prefix:"openssh-server", reference:"1:6.7p1-5+deb8u3")) flag++;
if (deb_check(release:"8.0", prefix:"openssh-server-udeb", reference:"1:6.7p1-5+deb8u3")) flag++;
if (deb_check(release:"8.0", prefix:"openssh-sftp-server", reference:"1:6.7p1-5+deb8u3")) flag++;
if (deb_check(release:"8.0", prefix:"ssh", reference:"1:6.7p1-5+deb8u3")) flag++;
if (deb_check(release:"8.0", prefix:"ssh-askpass-gnome", reference:"1:6.7p1-5+deb8u3")) flag++;
if (deb_check(release:"8.0", prefix:"ssh-krb5", reference:"1:6.7p1-5+deb8u3")) flag++;

if (flag)
{
  if (report_verbosity > 0) security_warning(port:0, extra:deb_report_get());
  else security_warning(0);
  exit(0);
}
else audit(AUDIT_HOST_NOT, "affected");
VendorProductVersionCPE
debiandebian_linuxopensshp-cpe:/a:debian:debian_linux:openssh
debiandebian_linux8.0cpe:/o:debian:debian_linux:8.0