Lesson 11 Flashcards
Network Address Allocation
Most networks use a mixture of static and dynamic address allocation.
Dynamic Host Configuration Protocol (DHCP)
provides an automatic method for network address allocation. - The key point about DHCP is that only one server should be offering addresses to any one group of hosts. If a rogue DHCP server is set up, it can perform DoS (as client machines will obtain an incorrect TCP/IP configuration) or be used to snoop network information.
DHCP starvation
type of DoS attack where a rogue client repeatedly requests new IP addresses using spoofed MAC addresses, with
the aim of exhausting the IP address pool.
Enabling the DHCP snooping port security feature on a switch can mitigate rogue DHCP
attacks.
DNS
Domain Name System (DNS) - esolves fully qualified domain names (FQDNs) to IP
addresses.
port 53
Domain hijacking
Domain hijacking is an attack where an adversary acquires a domain for a company’s
trading name or trademark, or perhaps some spelling variation thereof.
whois
(can help defend domain hijacking) The whois command can be
used to lookup domain registration information to try to detect misuse in other cases.
Uniform Resource Locator (URL) redirection
URLredirection refers to the use of HTTP redirects to open a page other than the one
the user requested. This is often used for legitimate purposes—to send the user to a
login page or to send a mobile device browser to a responsive version of the site, for
instance. If the redirect is not properly validated by the web application, an attacker
can craft a phishing link that might appear legitimate to a naïve user, such as:
https: //trusted.foo/login.php?url=”https://
tru5ted. foo”
Domain reputation
If your domain, website, or email servers have been hijacked, they are likely to be used
for spam or distributing malware. This will lead to complaints and the likelihood of the
domain being listed on a blacklist. You should set up monitoring using a site such as
talosintelligence.com/reputation_center to detect misuse early.
DNS Poisoning
DNS poisoning is an attack that compromises the process by which clients query
name servers to locate the IP address for a FQDN.
These are ways to do dns poisoning. i didn’t really look into these:
•Man in the Middle
•Rogue DNS server intercepts queries
•DNS client cache poisoning
•HOSTS file
•DNS server cache poisoning
•Corrupt cached records on DNS servers
•Spoof responses to queries by exploiting weak transaction ID generation
•DNS authoritative name server impersonation
DNS Security
- DNS server security
- Fault tolerance
- Authenticated recursive requests only
- Access control
- Patch management
- Prevent footprinting
- DNS Security Extensions (DNSSEC)
•DNS Security Extensions (DNSSEC)
help to mitigate against spoofing and poisoning
attacks by providing a validation process for DNS responses.
I left out some of the technical details
network directory
lists the subjects (principally users, computers, and services) and
objects (such as directories and files) available on the network plus the permissions
that subjects have over objects. A directory facilitates authentication and authorization,
and it is critical that it be maintained as a highly secure service.
LDAP
Most directory services
are based on the Lightweight Directory Access Protocol (LDAP), running over port
389. The basic protocol provides no security and all transmissions are in plaintext,
making it vulnerable to sniffing and man-in-the-middle attacks.
Authentication
(referred to as binding to the server) can be implemented in the following ways:
• No authentication—anonymous access is granted to the directory.
• Simple bind—the client must supply its distinguished name (DN) and password, but
these are passed as plaintext.
• Simple Authentication and Security Layer (SASL)—the client and server negotiate
the use of a supported authentication mechanism, such as Kerberos. The STARTTLS
command can be used to require encryption (sealing) and message integrity
(signing). This is the preferred mechanism for Microsoft’s Active Directory (AD)
implementation of LDAP.
LDAPS
LDAP Secure (LDAPS)—the server is installed with a digital certificate, which it uses to set up a secure tunnel for the user credential exchange. LDAPS uses port 636.
Two levels of access on LDAP
read-onlyaccess (query) and
read/write access (update).
This is implemented using an access
control policy, but the precise mechanism is vendor-specific and not specified by the
LDAP standards documentation.
Time Synchonization
Many applications on networks are time dependent and time critical.
Time critical services •Authentication •Logging •Task scheduling/backup •...
Network Time Protocol (NTP) [i have a seperate card for this
•Stratum 1 servers
•Stratum 2 servers
•Simple NTP (clients)
NTP
Network Time Protocol (NTP)
* Stratum 1 servers - taken from an atomic clock (top level) * Stratum 2 servers - most org will get ntp from stratum 2 servers - lower level * Simple NTP (clients) - Clients themselves usually obtain the time using modified form of the protocol (Simple NTP).
Simple Network Management Protocol (SNMP)
is a widely used framework for
management and monitoring. SNMP consists of an SNMP monitor and agents
- Agent runs on devices (switches, routers, servers) and maintains management information base (MIB)
- Monitor - Agent notifies SNMP monitor of events (traps)
- SNMP v1 and v2 feature no or weak authentication and no privacy
- SNMP v3 encryption and authentication
SNMP Versions
- SNMP v1 and v2 feature no or weak authentication and no privacy
- SNMP v3 encryption and authentication
Web server
=http server
HTTP
HTTP enables clients (typically web browsers) to request resources from an HTTP server.
how does a client connect to an HTTP server
TCP - using a TCP port
Http header and payload
Header - The response and request formats are defined in an HTTP header.
The HTTP payload - is usually used to serve HTML web pages, which are plain text files with coded tags
(HyperText Markup Language) describing how the page should be formatted.
http forms mechanism and stateless
- Forms mechanism allows client to upload data to the server
* Stateless protocol (does not record sessions) but expandedwith cookies and scripting
https
http used with ssl/tls