The Microsoft Skype for Business installation on the remote host is missing security updates. It is, therefore, affected by multiple vulnerabilities:
A session spoofing vulnerability exists. An attacker can exploit this to perform actions with the privileges of another user. (CVE-2021-24073)
A denial of service (DoS) vulnerability. An attacker can exploit this issue to cause the affected component to deny system or application services. (CVE-2021-24099)
#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from the Microsoft Security Updates API. The text
# itself is copyright (C) Microsoft Corporation.
#
include('compat.inc');
if (description)
{
script_id(146340);
script_version("1.6");
script_set_attribute(attribute:"plugin_modification_date", value:"2024/01/22");
script_cve_id("CVE-2021-24073", "CVE-2021-24099");
script_xref(name:"MSKB", value:"5000675");
script_xref(name:"MSKB", value:"5000688");
script_xref(name:"MSFT", value:"MS21-5000675");
script_xref(name:"MSFT", value:"MS21-5000688");
script_xref(name:"IAVA", value:"2021-A-0088-S");
script_name(english:"Security Updates for Microsoft Skype for Business (February 2021)");
script_set_attribute(attribute:"synopsis", value:
"The Microsoft Skype for Business installation on the remote host is affected by multiple vulnerabilities.");
script_set_attribute(attribute:"description", value:
"The Microsoft Skype for Business installation on the remote
host is missing security updates. It is, therefore, affected
by multiple vulnerabilities:
- A session spoofing vulnerability exists. An attacker can
exploit this to perform actions with the privileges of
another user. (CVE-2021-24073)
- A denial of service (DoS) vulnerability. An attacker can
exploit this issue to cause the affected component to
deny system or application services. (CVE-2021-24099)");
# https://support.microsoft.com/en-us/topic/description-of-the-security-update-for-skype-for-business-server-and-lync-server-february-9-2021-kb5000675-fa2b0688-72f6-4bde-b145-c48b5c503cec
script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?a701d748");
# https://support.microsoft.com/en-us/topic/description-of-the-security-update-for-skype-for-business-server-and-lync-server-february-9-2021-kb5000688-6e8431f9-6080-445c-80c2-34e6dde61bec
script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?ed486606");
script_set_attribute(attribute:"solution", value:
"Microsoft has released the following security updates to address this issue:
-KB5000675
-KB5000688");
script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:P/I:P/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:H/PR:L/UI:R/S:C/C:H/I:L/A:N");
script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
script_set_attribute(attribute:"cvss_score_source", value:"CVE-2021-24073");
script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
script_set_attribute(attribute:"exploit_available", value:"false");
script_set_attribute(attribute:"vuln_publication_date", value:"2021/02/09");
script_set_attribute(attribute:"patch_publication_date", value:"2021/02/09");
script_set_attribute(attribute:"plugin_publication_date", value:"2021/02/09");
script_set_attribute(attribute:"plugin_type", value:"local");
script_set_attribute(attribute:"cpe", value:"cpe:/a:microsoft:skype_for_business");
script_set_attribute(attribute:"stig_severity", value:"II");
script_end_attributes();
script_category(ACT_GATHER_INFO);
script_family(english:"Windows : Microsoft Bulletins");
script_copyright(english:"This script is Copyright (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.");
script_dependencies("office_installed.nasl", "microsoft_lync_server_installed.nasl", "smb_hotfixes.nasl", "ms_bulletin_checks_possible.nasl");
script_require_keys("SMB/MS_Bulletin_Checks/Possible");
script_require_ports(139, 445, "Host/patch_management_checks");
exit(0);
}
include('smb_func.inc');
include('smb_hotfixes.inc');
include('smb_hotfixes_fcheck.inc');
include('install_func.inc');
get_kb_item_or_exit('SMB/MS_Bulletin_Checks/Possible');
bulletin = 'MS21-02';
kbs = make_list(
'5000675',
'5000688'
);
if (get_kb_item('Host/patch_management_checks')) hotfix_check_3rd_party(bulletin:bulletin, kbs:kbs, severity:SECURITY_WARNING);
get_kb_item_or_exit('installed_sw/Microsoft Lync');
get_kb_item_or_exit('SMB/Registry/Uninstall/Enumerated', exit_code:1);
uninstall_list = get_kb_list('SMB/Registry/HKLM/SOFTWARE/Microsoft/Windows/CurrentVersion/Uninstall/*/DisplayName');
if (isnull(uninstall_list)) exit(1, 'Missing uninstall enumeration list.');
vuln = FALSE;
foreach name_kb (keys(uninstall_list))
{
prod = uninstall_list[name_kb];
version_kb = name_kb - '/DisplayName' + '/DisplayVersion';
if (
'Server' >< prod &&
(
'Core Components' >< prod ||
'Web Components Server' >< prod ||
'Macp Web Components' >< prod
)
)
{
if ('Skype for Business' >< prod)
{
if ('2019' >< prod)
{
version = get_kb_item(version_kb);
if (!isnull(version) && (ver_compare(ver:version, minver:'7.0.2046.0', fix:'7.0.2046.252') < 0))
{
vuln = TRUE;
kb = '5000675'; # This is one of the KBs. MS needs to clean up some linking stuff.
info = '\n Product : ' + prod +
'\n Installed Version : ' + version +
'\n Fixed Version : 7.0.2046.252\n';
hotfix_add_report(info, bulletin:bulletin, kb:kb);
}
}
else if ('2015' >< prod && 'Macp' >!< prod)
{
version = get_kb_item(version_kb);
if (!isnull(version) && (ver_compare(ver:version, minver:'6.0.9319.0', fix:'6.0.9319.601') < 0))
{
vuln = TRUE;
kb = '5000675'; # This is one of the KBs. MS needs to clean up some linking stuff.
# The other relevant KB is KB5000688 but only applies to 2015 and 2013
info = '\n Product : ' + prod +
'\n Installed Version : ' + version +
'\n Fixed Version : 6.0.9319.601\n';
hotfix_add_report(info, bulletin:bulletin, kb:kb);
}
}
}
else if ('Lync' >< prod && '2013' >< prod && 'Macp' >!< prod)
{
version = get_kb_item(version_kb);
if (!isnull(version) && (ver_compare(ver:version, minver:'5.0.8308.0', fix:'5.0.8308.1136') < 0))
{
vuln = TRUE;
kb = '5000675'; # This is one of the KBs. MS needs to clean up some linking stuff.
# The other relevant KB is KB5000688 but only applies to 2015 and 2013
info = '\n Product : ' + prod +
'\n Installed Version : ' + version +
'\n Fixed Version : 5.0.8308.1136\n';
hotfix_add_report(info, bulletin:bulletin, kb:kb);
}
}
}
}
if (vuln)
{
replace_kb_item(name:'SMB/Missing/'+bulletin, value:TRUE);
hotfix_security_warning();
exit(0);
}
else
{
audit(AUDIT_HOST_NOT, 'affected');
}
Vendor | Product | Version | CPE |
---|---|---|---|
microsoft | skype_for_business | cpe:/a:microsoft:skype_for_business |