TencentOS Server 2: openssh (TSSA-2025:0541)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Tencent Linux Security Advisory TSSA-2025:0541.
##

include('compat.inc');

if (description)
{
  script_id(247820);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2025/12/04");

  script_cve_id(
    "CVE-2018-20685",
    "CVE-2019-6109",
    "CVE-2019-6110",
    "CVE-2019-6111",
    "CVE-2020-14145",
    "CVE-2020-15778",
    "CVE-2023-48795",
    "CVE-2023-51385"
  );

  script_name(english:"TencentOS Server 2: openssh (TSSA-2025:0541)");

  script_set_attribute(attribute:"synopsis", value:
"The remote TencentOS Server 2 host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The version of Tencent Linux installed on the remote TencentOS Server 2 host is prior to tested version. It is,
therefore, affected by multiple vulnerabilities as referenced in the TSSA-2025:0541 advisory.

    Package updates are available for TencentOS Server 2 that fix the following vulnerabilities:

    CVE-2023-48795:
    An issue was discovered in OpenSSH 7.9. Due to missing character encoding in the progress display, a
    malicious server (or Man-in-The-Middle attacker) can employ crafted object names to manipulate the client
    output, e.g., by using ANSI control codes to hide additional files being transferred. This affects
    refresh_progress_meter() in progressmeter.c.

    CVE-2023-51385:
    An issue was discovered in OpenSSH 7.9. Due to the scp implementation being derived from 1983 rcp, the
    server chooses which files/directories are sent to the client. However, the scp client only performs
    cursory validation of the object name returned (only directory traversal attacks are prevented). A
    malicious scp server (or Man-in-The-Middle attacker) can overwrite arbitrary files in the scp client
    target directory. If recursive operation (-r) is performed, the server can manipulate subdirectories as
    well (for example, to overwrite the .ssh/authorized_keys file).

    CVE-2019-6109:
    In OpenSSH 7.9, due to accepting and displaying arbitrary stderr output from the server, a malicious
    server (or Man-in-The-Middle attacker) can manipulate the client output, for example to use ANSI control
    codes to hide additional files being transferred.

    CVE-2020-14145:
    In OpenSSH 7.9, scp.c in the scp client allows remote SSH servers to bypass intended access restrictions
    via the filename of . or an empty filename. The impact is modifying the permissions of the target
    directory on the client side.

    CVE-2019-6110:
    In ssh in OpenSSH before 9.6, OS command injection might occur if a user name or host name has shell
    metacharacters, and this name is referenced by an expansion token in certain situations. For example, an
    untrusted Git repository can have a submodule with shell metacharacters in a user name or host name.

    CVE-2019-6111:
    The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6 and other
    products, allows remote attackers to bypass integrity checks such that some packets are omitted (from the
    extension negotiation message), and a client and server may consequently end up with a connection for
    which some security features have been downgraded or disabled, aka a Terrapin attack. This occurs because
    the SSH Binary Packet Protocol (BPP), implemented by these extensions, mishandles the handshake phase and
    mishandles use of sequence numbers. For example, there is an effective attack against SSH's use of
    ChaCha20-Poly1305 (and CBC with Encrypt-then-MAC). The bypass occurs in [email protected] and
    (if CBC is used) the [email protected] MAC algorithms. This also affects Maverick Synergy Java SSH API
    before 3.1.0-SNAPSHOT, Dropbear through 2022.83, Ssh before 5.1.1 in Erlang/OTP, PuTTY before 0.80,
    AsyncSSH before 2.14.2, golang.org/x/crypto before 0.17.0, libssh before 0.10.6, libssh2 through 1.11.0,
    Thorn Tech SFTP Gateway before 3.4.6, Tera Term before 5.1, Paramiko before 3.4.0, jsch before 0.2.15,
    SFTPGo before 2.5.6, Netgate pfSense Plus through 23.09.1, Netgate pfSense CE through 2.7.2, HPN-SSH
    through 18.2.0, ProFTPD before 1.3.8b (and before 1.3.9rc2), ORYX CycloneSSH before 2.3.4, NetSarang
    XShell 7 before Build 0144, CrushFTP before 10.6.0, ConnectBot SSH library before 2.2.22, Apache MINA sshd
    through 2.11.0, sshj through 0.37.0, TinySSH through 20230101, trilead-ssh2 6401, LANCOM LCOS and
    LANconfig, FileZilla before 3.66.4, Nova before 11.8, PKIX-SSH before 14.4, SecureCRT before 9.4.3,
    Transmit5 before 5.10.4, Win32-OpenSSH before 9.5.0.0p1-Beta, WinSCP before 6.2.2, Bitvise SSH Server
    before 9.32, Bitvise SSH Client before 9.33, KiTTY through 0.76.1.13, the net-ssh gem 7.2.0 for Ruby, the
    mscdex ssh2 module before 1.15.0 for Node.js, the thrussh library before 0.35.1 for Rust, and the Russh
    crate before 0.40.2 for Rust.

    CVE-2020-15778:
    ** DISPUTED ** scp in OpenSSH through 8.3p1 allows command injection in the scp.c toremote function, as
    demonstrated by backtick characters in the destination argument. NOTE: the vendor reportedly has stated
    that they intentionally omit validation of anomalous argument transfers because that could stand a
    great chance of breaking existing workflows.

    CVE-2018-20685:
    The client side in OpenSSH 5.7 through 8.4 has an Observable Discrepancy leading to an information leak in
    the algorithm negotiation. This allows man-in-the-middle attackers to target initial connection attempts
    (where no host key for the server has been cached by the client). NOTE: some reports state that 8.5 and
    8.6 are also affected.

Tenable has extracted the preceding description block directly from the Tencent Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://mirrors.tencent.com/tlinux/errata/tssa-20250541.xml");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:A/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss4_supplemental", value:"CVSS:4.0/AU:N/R:A/V:D/RE:L/U:Amber");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:P");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2020-15778");
  script_set_attribute(attribute:"cvss4_score_source", value:"CVE-2023-48795");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2025/08/05");
  script_set_attribute(attribute:"patch_publication_date", value:"2025/08/05");
  script_set_attribute(attribute:"plugin_publication_date", value:"2025/08/11");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:tencent:tencentos_server:2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:tencent:tencentos_server:openssh");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Tencent Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2025 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info2.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/etc/os-release", "Host/TencentOS/rpm-list", "Host/cpu");

  exit(0);
}


include('rpm2.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_product = get_kb_item('installed_os/local/SSH/0/product');
if (isnull(os_product) || 'TencentOS' >!< os_product) audit(AUDIT_OS_NOT, 'TencentOS');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'TencentOS');
if (! preg(pattern:"^2([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'TencentOS 2.x', 'TencentOS ' + os_version);

if (!get_kb_item('Host/TencentOS/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'TencentOS', cpu);

var constraints = [
  {
    'release': '2',
    'pkgs': [
      {'reference':'openssh-7.4p1-23.tl2.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-7.4p1-23.tl2.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-askpass-7.4p1-23.tl2.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-askpass-7.4p1-23.tl2.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-cavs-7.4p1-23.tl2.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-cavs-7.4p1-23.tl2.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-clients-7.4p1-23.tl2.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-clients-7.4p1-23.tl2.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-debuginfo-7.4p1-23.tl2.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-debuginfo-7.4p1-23.tl2.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-keycat-7.4p1-23.tl2.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-keycat-7.4p1-23.tl2.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-ldap-7.4p1-23.tl2.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-ldap-7.4p1-23.tl2.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-server-7.4p1-23.tl2.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-server-7.4p1-23.tl2.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-server-sysvinit-7.4p1-23.tl2.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-server-sysvinit-7.4p1-23.tl2.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'pam_ssh_agent_auth-0.10.3-2.23.tl2', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'pam_ssh_agent_auth-0.10.3-2.23.tl2', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE}
    ]
  }
];

var os_release = get_one_kb_item('installed_os/local/SSH/0/release');
var os_sp = get_one_kb_item('Host/*/minor_release');

var flag = 0;
var reference;
var sp;
var _cpu;
var el_string;
var rpm_spec_vers_cmp;
var epoch;
var allowmaj;
var exists_check;
var cves;
foreach var constraint ( constraints ) {
  # Check that the target release is equal to the affected release
  if (!empty_or_null(constraint['release'])){
    if (constraint['release'] != os_release) continue;
  }
  if (!empty_or_null(constraint['sp'])){
    if (constraint['sp'] != os_sp) continue;
  }
  foreach var pkg ( constraint['pkgs'] ) {
    reference = NULL;
    sp = NULL;
    _cpu = NULL;
    el_string = NULL;
    rpm_spec_vers_cmp = NULL;
    epoch = NULL;
    allowmaj = NULL;
    exists_check = NULL;
    cves = NULL;
    if (!empty_or_null(pkg['reference'])) reference = pkg['reference'];
    if (!empty_or_null(pkg['sp'])) sp = pkg['sp'];
    if (!empty_or_null(pkg['cpu'])) _cpu = pkg['cpu'];
    if (!empty_or_null(pkg['el_string'])) el_string = pkg['el_string'];
    if (!empty_or_null(pkg['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = pkg['rpm_spec_vers_cmp'];
    if (!empty_or_null(pkg['epoch'])) epoch = pkg['epoch'];
    if (!empty_or_null(pkg['allowmaj'])) allowmaj = pkg['allowmaj'];
    if (!empty_or_null(pkg['exists_check'])) exists_check = pkg['exists_check'];
    if (!empty_or_null(pkg['cves'])) cves = pkg['cves'];
    if (reference &&
        ## (no known rpm to check OR known rpm_exists)
        (!exists_check || rpm_exists(rpm:exists_check)) &&
        rpm_check(sp:sp, cpu:_cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj, cves:cves)) flag++;
  }
}

if (flag)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_WARNING,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'openssh / openssh-askpass / openssh-cavs / etc');
}