Vulnerabilities > CVE-2018-20839 - Information Exposure vulnerability in multiple products

047910
CVSS 9.8 - CRITICAL
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
HIGH
Integrity impact
HIGH
Availability impact
HIGH
network
low complexity
systemd-project
netapp
CWE-200
critical
nessus

Summary

systemd 242 changes the VT1 mode upon a logout, which allows attackers to read cleartext passwords in certain circumstances, such as watching a shutdown, or using Ctrl-Alt-F1 and Ctrl-Alt-F2. This occurs because the KDGKBMODE (aka current keyboard mode) check is mishandled.

Vulnerable Configurations

Part Description Count
Application
Systemd_Project
1
Application
Netapp
2
OS
Netapp
1
Hardware
Netapp
1

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Subverting Environment Variable Values
    The attacker directly or indirectly modifies environment variables used by or controlling the target software. The attacker's goal is to cause the target software to deviate from its expected operation in a manner that benefits the attacker.
  • Footprinting
    An attacker engages in probing and exploration activity to identify constituents and properties of the target. Footprinting is a general term to describe a variety of information gathering techniques, often used by attackers in preparation for some attack. It consists of using tools to learn as much as possible about the composition, configuration, and security mechanisms of the targeted application, system or network. Information that might be collected during a footprinting effort could include open ports, applications and their versions, network topology, and similar information. While footprinting is not intended to be damaging (although certain activities, such as network scans, can sometimes cause disruptions to vulnerable applications inadvertently) it may often pave the way for more damaging attacks.
  • Exploiting Trust in Client (aka Make the Client Invisible)
    An attack of this type exploits a programs' vulnerabilities in client/server communication channel authentication and data integrity. It leverages the implicit trust a server places in the client, or more importantly, that which the server believes is the client. An attacker executes this type of attack by placing themselves in the communication channel between client and server such that communication directly to the server is possible where the server believes it is communicating only with a valid client. There are numerous variations of this type of attack.
  • Browser Fingerprinting
    An attacker carefully crafts small snippets of Java Script to efficiently detect the type of browser the potential victim is using. Many web-based attacks need prior knowledge of the web browser including the version of browser to ensure successful exploitation of a vulnerability. Having this knowledge allows an attacker to target the victim with attacks that specifically exploit known or zero day weaknesses in the type and version of the browser used by the victim. Automating this process via Java Script as a part of the same delivery system used to exploit the browser is considered more efficient as the attacker can supply a browser fingerprinting method and integrate it with exploit code, all contained in Java Script and in response to the same web page request by the browser.
  • Session Credential Falsification through Prediction
    This attack targets predictable session ID in order to gain privileges. The attacker can predict the session ID used during a transaction to perform spoofing and session hijacking.

Nessus

  • NASL familyHuawei Local Security Checks
    NASL idEULEROS_SA-2020-1062.NASL
    descriptionAccording to the versions of the xorg-x11-server packages installed, the EulerOS Virtualization for ARM 64 installation on the remote host is affected by the following vulnerabilities : - An incorrect permission check for -modulepath and -logfile options when starting Xorg X server allows unprivileged users with the ability to log in to the system via physical console to escalate their privileges and run arbitrary code under root privileges.(CVE-2018-14665) - systemd 242 changes the VT1 mode upon a logout, which allows attackers to read cleartext passwords in certain circumstances, such as watching a shutdown, or using Ctrl-Alt-F1 and Ctrl-Alt-F2. This occurs because the KDGKBMODE (aka current keyboard mode) check is mishandled.(CVE-2018-20839)(CVE-2019-1547) Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen2020-06-01
    modified2020-06-02
    plugin id132816
    published2020-01-13
    reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/132816
    titleEulerOS Virtualization for ARM 64 3.0.5.0 : xorg-x11-server (EulerOS-SA-2020-1062)
    code
    #
    # (C) Tenable Network Security, Inc.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(132816);
      script_version("1.2");
      script_cvs_date("Date: 2020/01/15");
    
      script_cve_id(
        "CVE-2018-14665",
        "CVE-2018-20839"
      );
    
      script_name(english:"EulerOS Virtualization for ARM 64 3.0.5.0 : xorg-x11-server (EulerOS-SA-2020-1062)");
      script_summary(english:"Checks the rpm output for the updated packages.");
    
      script_set_attribute(attribute:"synopsis", value:
    "The remote EulerOS Virtualization for ARM 64 host is missing multiple security
    updates.");
      script_set_attribute(attribute:"description", value:
    "According to the versions of the xorg-x11-server packages installed,
    the EulerOS Virtualization for ARM 64 installation on the remote host
    is affected by the following vulnerabilities :
    
      - An incorrect permission check for -modulepath and
        -logfile options when starting Xorg X server allows
        unprivileged users with the ability to log in to the
        system via physical console to escalate their
        privileges and run arbitrary code under root
        privileges.(CVE-2018-14665)
    
      - systemd 242 changes the VT1 mode upon a logout, which
        allows attackers to read cleartext passwords in certain
        circumstances, such as watching a shutdown, or using
        Ctrl-Alt-F1 and Ctrl-Alt-F2. This occurs because the
        KDGKBMODE (aka current keyboard mode) check is
        mishandled.(CVE-2018-20839)(CVE-2019-1547)
    
    Note that Tenable Network Security has extracted the preceding
    description block directly from the EulerOS security advisory. Tenable
    has attempted to automatically clean and format it as much as possible
    without introducing additional issues.");
      # https://developer.huaweicloud.com/ict/en/site-euleros/euleros/security-advisories/EulerOS-SA-2020-1062
      script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?1ac7ca3f");
      script_set_attribute(attribute:"solution", value:
    "Update the affected xorg-x11-server packages.");
      script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C");
      script_set_cvss_temporal_vector("CVSS2#E:F/RL:OF/RC:C");
      script_set_cvss3_base_vector("CVSS:3.0/AV:P/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H");
      script_set_cvss3_temporal_vector("CVSS:3.0/E:F/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:"metasploit_name", value:'Xorg X11 Server SUID modulepath Privilege Escalation');
      script_set_attribute(attribute:"exploit_framework_metasploit", value:"true");
    
      script_set_attribute(attribute:"patch_publication_date", value:"2020/01/13");
      script_set_attribute(attribute:"plugin_publication_date", value:"2020/01/13");
    
      script_set_attribute(attribute:"plugin_type", value:"local");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:xorg-x11-server-Xorg");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:xorg-x11-server-common");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:huawei:euleros:uvp:3.0.5.0");
      script_set_attribute(attribute:"generated_plugin", value:"current");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_family(english:"Huawei Local Security Checks");
    
      script_copyright(english:"This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.");
    
      script_dependencies("ssh_get_info.nasl");
      script_require_keys("Host/local_checks_enabled", "Host/cpu", "Host/EulerOS/release", "Host/EulerOS/rpm-list", "Host/EulerOS/uvp_version");
    
      exit(0);
    }
    
    include("audit.inc");
    include("global_settings.inc");
    include("rpm.inc");
    
    if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
    
    release = get_kb_item("Host/EulerOS/release");
    if (isnull(release) || release !~ "^EulerOS") audit(AUDIT_OS_NOT, "EulerOS");
    uvp = get_kb_item("Host/EulerOS/uvp_version");
    if (uvp != "3.0.5.0") audit(AUDIT_OS_NOT, "EulerOS Virtualization 3.0.5.0");
    if (!get_kb_item("Host/EulerOS/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);
    
    cpu = get_kb_item("Host/cpu");
    if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
    if ("x86_64" >!< cpu && cpu !~ "^i[3-6]86$" && "aarch64" >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "EulerOS", cpu);
    if ("aarch64" >!< cpu) audit(AUDIT_ARCH_NOT, "aarch64", cpu);
    
    flag = 0;
    
    pkgs = ["xorg-x11-server-Xorg-1.20.1-4.h4.eulerosv2r8",
            "xorg-x11-server-common-1.20.1-4.h4.eulerosv2r8"];
    
    foreach (pkg in pkgs)
      if (rpm_check(release:"EulerOS-2.0", reference:pkg)) flag++;
    
    if (flag)
    {
      security_report_v4(
        port       : 0,
        severity   : SECURITY_HOLE,
        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, "xorg-x11-server");
    }
    
  • NASL familyHuawei Local Security Checks
    NASL idEULEROS_SA-2020-1037.NASL
    descriptionAccording to the version of the xorg-x11-server packages installed, the EulerOS installation on the remote host is affected by the following vulnerability : - systemd 242 changes the VT1 mode upon a logout, which allows attackers to read cleartext passwords in certain circumstances, such as watching a shutdown, or using Ctrl-Alt-F1 and Ctrl-Alt-F2. This occurs because the KDGKBMODE (aka current keyboard mode) check is mishandled.(CVE-2018-20839) Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen2020-05-03
    modified2020-01-02
    plugin id132630
    published2020-01-02
    reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/132630
    titleEulerOS 2.0 SP8 : xorg-x11-server (EulerOS-SA-2020-1037)
    code
    #
    # (C) Tenable Network Security, Inc.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(132630);
      script_version("1.3");
      script_set_attribute(attribute:"plugin_modification_date", value:"2020/05/01");
    
      script_cve_id(
        "CVE-2018-20839"
      );
    
      script_name(english:"EulerOS 2.0 SP8 : xorg-x11-server (EulerOS-SA-2020-1037)");
      script_summary(english:"Checks the rpm output for the updated package.");
    
      script_set_attribute(attribute:"synopsis", value:
    "The remote EulerOS host is missing a security update.");
      script_set_attribute(attribute:"description", value:
    "According to the version of the xorg-x11-server packages installed,
    the EulerOS installation on the remote host is affected by the
    following vulnerability :
    
      - systemd 242 changes the VT1 mode upon a logout, which
        allows attackers to read cleartext passwords in certain
        circumstances, such as watching a shutdown, or using
        Ctrl-Alt-F1 and Ctrl-Alt-F2. This occurs because the
        KDGKBMODE (aka current keyboard mode) check is
        mishandled.(CVE-2018-20839)
    
    Note that Tenable Network Security has extracted the preceding
    description block directly from the EulerOS security advisory. Tenable
    has attempted to automatically clean and format it as much as possible
    without introducing additional issues.");
      # https://developer.huaweicloud.com/ict/en/site-euleros/euleros/security-advisories/EulerOS-SA-2020-1037
      script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?f2f1bbbb");
      script_set_attribute(attribute:"solution", value:
    "Update the affected xorg-x11-server package.");
      script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:N");
      script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
      script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H");
      script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
      script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
    
      script_set_attribute(attribute:"patch_publication_date", value:"2020/01/02");
      script_set_attribute(attribute:"plugin_publication_date", value:"2020/01/02");
    
      script_set_attribute(attribute:"plugin_type", value:"local");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:xorg-x11-server-Xephyr");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:xorg-x11-server-Xorg");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:xorg-x11-server-Xvfb");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:xorg-x11-server-Xwayland");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:xorg-x11-server-common");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:huawei:euleros:2.0");
      script_set_attribute(attribute:"generated_plugin", value:"current");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_family(english:"Huawei Local Security Checks");
    
      script_copyright(english:"This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.");
    
      script_dependencies("ssh_get_info.nasl");
      script_require_keys("Host/local_checks_enabled", "Host/EulerOS/release", "Host/EulerOS/rpm-list", "Host/EulerOS/sp");
      script_exclude_keys("Host/EulerOS/uvp_version");
    
      exit(0);
    }
    
    include("audit.inc");
    include("global_settings.inc");
    include("rpm.inc");
    
    if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
    
    release = get_kb_item("Host/EulerOS/release");
    if (isnull(release) || release !~ "^EulerOS") audit(AUDIT_OS_NOT, "EulerOS");
    if (release !~ "^EulerOS release 2\.0(\D|$)") audit(AUDIT_OS_NOT, "EulerOS 2.0");
    
    sp = get_kb_item("Host/EulerOS/sp");
    if (isnull(sp) || sp !~ "^(8)$") audit(AUDIT_OS_NOT, "EulerOS 2.0 SP8");
    
    uvp = get_kb_item("Host/EulerOS/uvp_version");
    if (!empty_or_null(uvp)) audit(AUDIT_OS_NOT, "EulerOS 2.0 SP8", "EulerOS UVP " + uvp);
    
    if (!get_kb_item("Host/EulerOS/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);
    
    cpu = get_kb_item("Host/cpu");
    if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
    if ("x86_64" >!< cpu && cpu !~ "^i[3-6]86$" && "aarch64" >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "EulerOS", cpu);
    if ("aarch64" >!< cpu) audit(AUDIT_ARCH_NOT, "aarch64", cpu);
    
    flag = 0;
    
    pkgs = ["xorg-x11-server-Xephyr-1.20.1-4.h4.eulerosv2r8",
            "xorg-x11-server-Xorg-1.20.1-4.h4.eulerosv2r8",
            "xorg-x11-server-Xvfb-1.20.1-4.h4.eulerosv2r8",
            "xorg-x11-server-Xwayland-1.20.1-4.h4.eulerosv2r8",
            "xorg-x11-server-common-1.20.1-4.h4.eulerosv2r8"];
    
    foreach (pkg in pkgs)
      if (rpm_check(release:"EulerOS-2.0", sp:"8", reference:pkg)) flag++;
    
    if (flag)
    {
      security_report_v4(
        port       : 0,
        severity   : SECURITY_WARNING,
        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, "xorg-x11-server");
    }