Overview: Identify the Internet protocols and standards Identify common vulnerabilities and countermeasures Identify specific IIS/WWW/FTP concerns Identify specific Exchange/SMTP/POP service concerns Identify specific RAS/dial-in/dial-out concerns Module 9

TCP/IP Architecture

l FTP l Telnet (Add-on) l NFS (Add-on) l SMTP (Exchange, Lotus MTA, NTMail…) l SNMP l Increasingly more TCP/IP services are becoming available in the NT environment l Result: substantial increased in the threat of unauthorized remote access TCP/IP Services

l RFC , ,1035 SUBJECT User Datagram Protocal (UDP) Trivial File Transfer Protocol (TFTP) Internet Protocol (IP) Internet Control Message Protocol (ICMP) Transmission Control Protocol (TCP) Address Resolution Protocol (ARP) Telnet Protocol (TELNET) IP over Ethernet IP Broadcast Datagrams Internet Standard Subnetting Procedure File Transfer Protocol Requirements for Internet Gateways Domain Name Service (DNS) RFCs & Open Standards

l Service Echo Chargen FTP Telnet SMTP HTTP nbname nbdatagram nbsession Port , TCP/IP Services Deserving Special Focus

l Built on TCP/IPv4 suite (Basic Clear Text) l Data storage locations are left on vulnerable drives l Data files that grow are left on system drive l Services that use weak authentication l Services are run on PDC –Reward from compromise is infinitely great –SAM database is used for authentication l Source IP filtering is not used when appropriate Common Application- Vulnerabilities

l Use TCP/IPv6 when available (full encryption) l Move data and logs to non- system disk and delete default share l Chose the strongest authentication possible l Run Internet Services on servers with no trust, not DCs l Disable inappropriate services on Servers providing Internet Services. l Use source IP filtering for all, local only, services Common Application- Counter Measures

l Internet Information Server (IIS) WWW Server l IIS FTP Server l IIS Gopher Server l Exchange SMTP, POP, LDAP, l Remote Access Server (RAS) PPP & PPTP l Certificate Server Applications for Internet Services

l IIS V2, V3, V4 l Provides Internet Service Daemons; www, ftp, gopher –V4 does not provide gopher l Can be managed from a central location –V2 & V3 Use Internet Service Manager –V4 Uses Microsoft Management Console(MMC) as snap-in l Uses NT Security Model l WWW Security features include: –NT Challenge Authentication –SSL ( Internet Information Server (IIS)

l Provides for Strong Authentication l Provides for HTTPS (Secure) Pages l Allows IP source filtering IIS

With Property Sheets You Can Establish Logon Requirements Configure Access Permissions Specify Home Directories Create Multiple Virtual Servers On One Computer Setting Encryption Options Configure Event Logging Options View Current Sessions Enable or Disable Server Access By IP Address

FTP makes all objects in the file structure accessible! Access permission = permissions assigned to account used to gain FTP access and file/directory permission (conjunctive rule) A Special Concern: FTP

l Account to be used for FTP access can be misused similarly to the Guest account FTP users are members of Everyone group Inbound FTP authentication can be performed by the source host if not configured otherwise Passwords for outbound FTP are transmitted in clear text A Special Concern: FTP

l HTTP input overflow can allow unauthorized users to execute commands CGI scripts can allow commands to be written to.BAT files, resulting in execution of commands not intended for execution on web servers Some types of HTTP access are to a user ID (as in FTP ) Problems with NT-Based Web Servers

l Serious concern: NT web servers or firewalls running within an NT domain (and, thus, effectively within NT’s security perimeter) Recommendations: - Run each firewall as a standalone NT platform - Run Web servers as standalone NT platforms or as part of a Web server domain - Do not mix internal and external Web servers in the same domain TCP/IP Services and NT Domains

l Recommendations for Controlling TCP/IP Services IIS

l Security Approach

IIS

NT Security for System Administrators

IIS