CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
AV:L/AC:L/Au:N/C:C/I:C/A:C
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS
Percentile
38.6%
The version of Cisco AnyConnect Secure Mobility Client installed on the remote Windows host is 4.0.x prior to 4.3.05017 or 4.4.x prior to 4.4.00243. It is, therefore, affected by a privilege escalation vulnerability in the Start Before Logon (SBL) module due to insufficient access controls. A local attacker can exploit this to open Internet Explorer with SYSTEM level privileges.
Note that the SBL module is not installed by default.
#
# (C) Tenable Network Security, Inc.
#
include("compat.inc");
if (description)
{
script_id(97226);
script_version("1.7");
script_cvs_date("Date: 2019/11/13");
script_cve_id("CVE-2017-3813");
script_bugtraq_id(96145);
script_xref(name:"CISCO-SA", value:"cisco-sa-20170208-anyconnect");
script_xref(name:"CISCO-BUG-ID", value:"CSCvc43976");
script_name(english:"Cisco AnyConnect Secure Mobility Client 4.0.x < 4.3.05017 / 4.4.x < 4.4.00243 SBL Module Privilege Escalation");
script_summary(english:"Checks the version of the Cisco AnyConnect client and affected module.");
script_set_attribute(attribute:"synopsis", value:
"A VPN application installed on the remote host is affected by a
privilege escalation vulnerability.");
script_set_attribute(attribute:"description", value:
"The version of Cisco AnyConnect Secure Mobility Client installed on
the remote Windows host is 4.0.x prior to 4.3.05017 or 4.4.x prior to
4.4.00243. It is, therefore, affected by a privilege escalation
vulnerability in the Start Before Logon (SBL) module due to
insufficient access controls. A local attacker can exploit this to
open Internet Explorer with SYSTEM level privileges.
Note that the SBL module is not installed by default.");
# https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170208-anyconnect
script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?5b0700b1");
script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvc43976");
script_set_attribute(attribute:"solution", value:
"Upgrade to Cisco AnyConnect Secure Mobility Client version 4.3.05017 /
4.4.00243 or later. Alternatively, either remove the SBL module or set
'UseStartBeforeLogon' to false in the client profile XML file.");
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:POC/RL:OF/RC:C");
script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/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:"cvss_score_source", value:"CVE-2017-3813");
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:"2017/02/08");
script_set_attribute(attribute:"patch_publication_date", value:"2017/02/08");
script_set_attribute(attribute:"plugin_publication_date", value:"2017/02/17");
script_set_attribute(attribute:"plugin_type", value:"local");
script_set_attribute(attribute:"cpe", value:"cpe:/a:cisco:anyconnect_secure_mobility_client");
script_end_attributes();
script_category(ACT_GATHER_INFO);
script_family(english:"Windows");
script_copyright(english:"This script is Copyright (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof.");
script_dependencies("cisco_anyconnect_vpn_installed.nasl");
script_require_keys("installed_sw/Cisco AnyConnect Secure Mobility Client", "SMB/Registry/Enumerated");
script_require_ports(139, 445);
exit(0);
}
include("audit.inc");
include("misc_func.inc");
include("smb_func.inc");
include("smb_hotfixes.inc");
include("smb_hotfixes_fcheck.inc");
include("smb_reg_query.inc");
include("install_func.inc");
get_kb_item_or_exit("SMB/Registry/Enumerated");
app_name = "Cisco AnyConnect Secure Mobility Client";
install = get_single_install(app_name:app_name, exit_if_unknown_ver:TRUE);
path = install['path'];
ver = install['version'];
fix = '';
errors = make_list();
if (ver =~ "^4\.4\." && ver_compare(ver:ver, fix:'4.4.243', strict:FALSE) < 0)
fix = '4.4.243';
else if (ver =~ "^4\.[0-3]\." && ver_compare(ver:ver, fix:'4.3.5017', strict:FALSE) < 0)
fix = '4.3.5017';
if (empty(fix))
audit(AUDIT_INST_PATH_NOT_VULN, app_name, ver, path);
# Check for module uninstall entry
module = "Cisco AnyConnect Start Before Login Module";
module_path = NULL;
display_names = get_kb_list("SMB/Registry/HKLM/SOFTWARE/Microsoft/Windows/CurrentVersion/Uninstall/*/DisplayName");
foreach key (keys(display_names))
{
if (display_names[key] == module)
{
key = key - "DisplayName" + "InstallLocation";
module_path = get_kb_item(key);
break;
}
}
if (empty_or_null(module_path)) audit(AUDIT_NOT_INST, module);
# Check for module DLL
registry_init();
dlls = make_list("vpnplap.dll", "vpnplap64.dll");
dll_found = FALSE;
foreach dll (dlls)
{
dll = module_path + dll;
if (hotfix_file_exists(path:dll))
{
dll_found = TRUE;
break;
}
}
if (!dll_found)
{
hotfix_check_fversion_end();
audit(AUDIT_NOT_INST, module);
}
# Check each profile
programdata = hotfix_get_programdata(exit_on_fail:TRUE);
profile_dir = hotfix_append_path(path:programdata, value:"\Cisco\Cisco AnyConnect Secure Mobility Client\Profile");
sbl_profiles = make_list();
share = hotfix_path2share(path:profile_dir);
base_dir = ereg_replace(string:profile_dir, pattern:"^\w:(.*)", replace:"\1");
profiles = list_dir(basedir:base_dir, level:1, file_pat:".*\.xml$", share:share);
foreach profile (profiles)
{
profile = (share - '$') + ':' + profile;
contents = hotfix_get_file_contents(profile);
error = hotfix_handle_error(error_code:contents['error'], file:profile, exit_on_fail:FALSE);
if (error)
{
errors = make_list(errors, error);
continue;
}
pattern = "^\s*<UseStartBeforeLogon.*>true</UseStartBeforeLogon>";
if (preg(string:contents['data'], pattern:pattern, icase:TRUE, multiline:TRUE))
sbl_profiles = make_list(sbl_profiles, profile);
}
hotfix_check_fversion_end();
if (max_index(sbl_profiles) == 0)
{
if (max_index(errors) == 0)
audit(AUDIT_HOST_NOT, "affected because the 'UseStartBeforeLogon' option is not enabled on any Cisco AnyConnect profiles");
else if (max_index(errors) == 1)
exit(1, "The following error has occurred : " + errors[0]);
else
exit(1, "The following errors have occurred : " + join(errors, sep:";"));
}
wording = NULL;
if (max_index(sbl_profiles) == 1)
wording = 'profile has';
else
wording = 'profiles have';
report =
'\n Cisco bug ID : CSCvc43976' +
'\n Path : ' + path +
'\n Installed version : ' + ver +
'\n Fixed version : ' + fix +
'\n' +
'\nThe following Cisco AnyConnect ' + wording + ' the \'UseStartBeforeLogon\' option enabled :\n' +
'\n - ' + join(sbl_profiles, sep:'\n - ');
security_report_v4(port:kb_smb_transport(), severity:SECURITY_HOLE, extra:report);
Vendor | Product | Version | CPE |
---|---|---|---|
cisco | anyconnect_secure_mobility_client | cpe:/a:cisco:anyconnect_secure_mobility_client |
CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
AV:L/AC:L/Au:N/C:C/I:C/A:C
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS
Percentile
38.6%