- Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
- **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
**Bug bounty tip**: **sign up** for **Intigriti**, a premium **bug bounty platform created by hackers, for hackers**! Join us at [**https://go.intigriti.com/hacktricks**](https://go.intigriti.com/hacktricks) today, and start earning bounties up to **$100,000**!
This is the **easiest** and **fastest** way to discover if a host is up or not.\
You could try to send some **ICMP** packets and **expect responses**. The easiest way is just sending an **echo request** and expect from the response. You can do that using a simple `ping`or using `fping`for **ranges**.\
You could also use **nmap** to send other types of ICMP packets (this will avoid filters to common ICMP echo request-response).
It's very common to find that all kind of ICMP packets are being filtered. Then, all you can do to check if a host is up is **try to find open ports**. Each host has **65535 ports**, so, if you have a "big" scope you **cannot** test if **each port** of each host is open or not, that will take too much time.\
Then, what you need is a **fast port scanner** ([masscan](https://github.com/robertdavidgraham/masscan)) and a list of the **ports more used:**
You could also try to check for some **UDP port open** to decide if you should **pay more attention** to a **host.** As UDP services usually **don't respond** with **any data** to a regular empty UDP probe packet it is difficult to say if a port is being filtered or open. The easiest way to decide this is to send a packet related to the running service, and as you don't know which service is running, you should try the most probable based on the port number:
The nmap line proposed before will test the **top 1000 UDP ports** in every host inside the **/24** range but even only this will take **>20min**. If need **fastest results** you can use [**udp-proto-scanner**](https://github.com/portcullislabs/udp-proto-scanner): `./udp-proto-scanner.pl 199.66.11.53/24` This will send these **UDP probes** to their **expected port** (for a /24 range this will just take 1 min): _DNSStatusRequest, DNSVersionBindReq, NBTStat, NTPRequest, RPCCheck, SNMPv3GetRequest, chargen, citrix, daytime, db2, echo, gtpv1, ike,ms-sql, ms-sql-slam, netop, ntp, rpc, snmp-public, systat, tftp, time, xdmcp._
If you are inside the network one of the first things you will want to do is to **discover other hosts**. Depending on **how much noise** you can/want to do, different actions could be performed:
Note that the techniques commented in [_**Discovering hosts from the outside**_](./#discovering-hosts-from-the-outside) (_TCP/HTTP/UDP/SCTP Port Discovery_) can be also **applied here**.\
* If you **ping** a **subnet broadcast address** the ping should be arrive to **each host** and they could **respond** to **you**: `ping -b 10.10.5.255`
* Pinging the **network broadcast address** you could even find hosts inside **other subnets**: `ping -b 255.255.255.255`
* Use the `-PEPM` flag of `nmap`to perform host discovery sending **ICMPv4 echo**, **timestamp**, and **subnet mask requests:**`nmap -PEPM -sP –vvv -n 10.12.5.0/24`
Wake On Lan is used to **turn on** computers through a **network message**. The magic packet used to turn on the computer is only a packet where a **MAC Dst** is provided and then it is **repeated 16 times** inside the same paket.\
Then this kind of packets are usually sent in an **ethernet 0x0842** or in a **UDP packet to port 9**.\
If **no \[MAC]** is provided, the packet is sent to **broadcast ethernet** (and the broadcast MAC will be the one being repeated).
* Send a **UDP packet** and check for the response _**ICMP unreachable**_ if the port is **closed** (in several cases ICMP will be **filtered** so you won't receive any information inf the port is close or open).
* Send a **formatted datagrams** to elicit a response from a **service** (e.g., DNS, DHCP, TFTP, and others, as listed in _nmap-payloads_). If you receive a **response**, then, the port is **open**.
SCTP sits alongside TCP and UDP. Intended to provide **transport** of **telephony** data over **IP**, the protocol duplicates many of the reliability features of Signaling System 7 (SS7), and underpins a larger protocol family known as SIGTRAN. SCTP is supported by operating systems including IBM AIX, Oracle Solaris, HP-UX, Linux, Cisco IOS, and VxWorks.
Misconfigured routers, firewalls, and network devices sometimes **respond** to network probes **using nonpublic source addresses**. You can use _tcpdump_ used to **identify packets** received from **private addresses** during testing. In this case, the _eth2_ interface in Kali Linux is **addressable** from the **public Internet** (If you are **behind** a **NAT** of a **Firewall** this kind of packets are probably going to be **filtered**).
Sniffing you can learn details of IP ranges, subnet sizes, MAC addresses, and hostnames by reviewing captured frames and packets. If the network is misconfigured or switching fabric under stress, attackers can capture sensitive material via passive network sniffing.
If a switched Ethernet network is configured properly, you will only see broadcast frames and material destined for your MAC address.
ARP Spoofing consist on sending gratuitous ARPResponses to indicate that the IP of a machine has the MAC of our device. Then, the victim will change the ARP table and will contact our machine every time it wants to contact the IP spoofed.
Overflow the switch’s CAM table sending a lot of packets with different source mac address. When the CAM table is full the switch start behaving like a hub (broadcasting all the traffic).
Many switches support the Dynamic Trunking Protocol (DTP) by default, however, which an adversary can abuse to **emulate a switch and receive traffic across all VLANs**. The tool [_**dtpscan.sh**_](https://github.com/commonexploits/dtpscan) can sniff an interface and **reports if switch is in Default mode, trunk, dynamic, auto or access mode** (this is the only one that would avoid VLAN hopping). The tool will indicate if the switch is vulnerable or not.
If it was discovered that the the network is vulnerable, you can use _**Yersinia**_ to launch an "**enable trunking**" using protocol "**DTP**" and you will be able to see network packets from all the VLANs.
The discussed attack of **Dynamic Trunking and creating virtual interfaces an discovering hosts inside** other VLANs are **automatically performed** by the tool: [**https://github.com/nccgroup/vlan-hopping---frogger**](https://github.com/nccgroup/vlan-hopping---frogger)
If an attacker knows the value of the **MAC, IP and VLAN ID of the victim host**, he could try to **double tag a frame** with its designated VLAN and the VLAN of the victim and send a packet. As the **victim won't be able to connect back** with the attacker, so the **best option for the attacker is communicate via UDP** to protocols that can perform some interesting actions (like SNMP).
Another option for the attacker is to launch a **TCP port scan spoofing an IP controlled by the attacker and accessible by the victim** (probably through internet). Then, the attacker could sniff in the second host owned by him if it receives some packets from the victim.
In guest wireless networks and other environments, private VLAN (also known as _port isolation_) settings are used to **prevent peers from interacting** (i.e., clients **connect to a wireless access point but cannot address one another**). Depending on network ACLs (or lack thereof), it might be possible to send IP packets up to a router, which are then forwarded back to a neighbouring peer.
This attack will send a **specially crafted packet to the IP of a client but with the MAC of the router**. Then, the **router will redirect the packet to the client**. As in _Double Tagging Attacks_ you can exploit this vulnerability by controlling a host accessible by the victim.
Sending a lot of BPDUs TCP (Topology Change Notification) or Conf (the BPDUs that are sent when the topology is created) the switches are overloaded and stop working correctly.
When a TCP is sent, the CAM table of the switches will be deleted in 15s. Then, if you are sending continuously this kind of packets, the CAM table will be restarted continuously (or every 15segs) and when it is restarted, the switch behaves as a hub
The attacker simulates the behaviour of a switch to become the STP root of the network. Then, more data will pass through him. This is interesting when you are connected to two different switches.\
**If the attacker is connected to 2 switches he can be the root of the new tree and all the traffic between those switches will pass through him** (a MITM attack will be performed).
yersinia stp -attack 6 #This will cause a DoS as the layer 2 packets wont be forwarded. You can use Ettercap to forward those packets "Sniff" --> "Bridged sniffing"
CISCO Discovery Protocol is the protocol used by CISCO devices to talk among them, **discover who is alive** and what features does they have. You can make a DoS attack to a CISCO switch by exhausting the device memory simulating real CISCO devices.
Although intended for use by the employees’ Voice over Internet Protocol (VoIP) phones, modern VoIP devices are increasingly integrated with IoT devices. Many employees can now unlock doors using a special phone number, control the room’s thermostat...
The tool [**voiphopper**](http://voiphopper.sourceforge.net) mimics the behavior of a VoIP phone in Cisco, Avaya, Nortel, and Alcatel-Lucent environments. It automatically discovers the correct VLAN ID for the voice network using one of the device discovery protocols it supports, such as the Cisco Discovery Protocol (CDP), the Dynamic Host Configuration Protocol (DHCP), Link Layer Discovery Protocol Media Endpoint Discovery (LLDP-MED), and 802.1Q ARP.
**VoIP Hopper** supports **three** CDP modes. The **sniff** mode inspects the network packets and attempts to locate the VLAN ID. To use it, set the **`-c`** parameter to `0`. The **spoof** mode generates custom packets similar to the ones a real VoIP device would transmit in the corporate network. To use it, set the **`-c`** parameter to **`1`**. The spoof with a **pre-madepacket** mode sends the same packets as a Cisco 7971G-GE IP phone. To use it, set the **`-c`** parameter to **`2`**.
We use the last method because it’s the fastest approach. The **`-i`** parameter specifies the attacker’s **network****interface**, and the **`-E`** parameter specifies the **name of the VOIP device** being imitated. We chose the name SEP001EEEEEEEEE, which is compatible with the Cisco naming format for VoIP phones. The format consists of the word “SEP” followed by a MAC address. In corporate environments, you can imitate an existing VoIP device by looking at the MAC label on the back of the phone; by pressing the Settings button and selecting the Model Information option on the phone’s display screen; or by attaching the VoIP device’s Ethernet cable to your laptop and observing the device’s CDP requests using Wireshark.
```bash
voiphopper -i eth1 -E 'SEP001EEEEEEEEE ' -c 2
```
If the tool executes successfully, the **VLAN network will assign an IPv4 address to the attacker’s device**.
**Two types of DoS** could be performed against DHCP servers. The first one consists on **simulate enough fake hosts to use all the possible IP addresses**.\
This attack will work only if you can see the responses of the DHCP server and complete the protocol (**Discover** (Comp) --> **Offer** (server) --> **Request** (Comp) --> **ACK** (server)). For example, this is **not possible in Wifi networks**.
Another way to perform a DHCP DoS is to send a **DHCP-RELEASE packet using as source code every possible IP**. Then, the server will think that everybody has finished using the IP.
```bash
yersinia dhcp -attack 1
yersinia dhcp -attack 3 #More parameters are needed
```
A more automatic way of doing this is using the tool [DHCPing](https://github.com/kamorin/DHCPig)
You could use the mentioned DoS attacks to force clients to obtain new leases within the environment, and exhaust legitimate servers so that they become unresponsive. So when the legitimate try to reconnect, **you can server malicious values mentioned in the next attack**.
You can use Responder DHCP script (_/usr/share/responder/DHCP.py_) to establish a rogue DHCP server. Setting a malicious gateway is not ideal, because the hijacked connection is only half-duplex (i.e., we capture egress packets from the client, but not the responses from the legitimate gateway). As such, I would recommend setting a rogue DNS or WPAD server to capture HTTP traffic and credentials in particular.
If the attacker if between the victim and the authentication server, he could try to degrade (if necessary) the authentication protocol to EAP-MD5 and capture the authentication attempt. Then, he could brute-force this using:
Hot Standby Routing Protocol (HSRP) and the Virtual Router Redundancy Protocol (VRRP) are used in high-availability environments to provide failover support. Routers send packets to local multicast groups announcing configuration and priority details.
HSRP is a proprietary Cisco protocol with no RFC, whereas VRRP is standardized. To evaluate HSRP and VRRP support within an environment, use a network sniffer to capture the management traffic. You can use a number of tools to craft HSRP messages (including Scapy and Yersinia), but only Loki provides VRRP support at this time.
Three versions of the Routing Information Protocol (RIP) exist—RIP, RIPv2, and RIPng. RIP and RIPv2 use UDP datagrams sent to peers via port 520, whereas RIPng broadcasts datagrams to UDP port 521 via IPv6 multicast. RIPv2 introduced MD5 authentication support. RIPng does not incorporate native authentication; rather, it relies on optional IPsec AH and ESP headers within IPv6.
The Enhanced Interior Gateway Routing Protocol (EIGRP) is Cisco proprietary and can be run with or without authentication. \_\_[Coly](https://code.google.com/p/coly/) supports capture of EIGRP broadcasts and injection of packets to manipulate routing configuration.
Most Open Shortest Path First (OSPF) implementations use MD5 to provide authentication between routers. Loki and John the Ripper can capture and attack MD5 hashes to reveal the key, which can then be used to advertise new routes. The route parameters are set by using the _Injection_ tab, and the key set under _Connection_.
You can find some more information about network attacks [here](https://github.com/Sab0tag3d/MITM-cheatsheet). _\*\*(TODO: Read it all and all new attacks if any)_
ICMP Redirect consist on sending an ICMP packet type 1 code 5 that indicates that the attacker is the best way to reach an IP. Then, when the victim wants to contact the IP, it will send the packet through the attacker.
```bash
Ettercap
icmp_redirect
hping3 [VICTIM IP ADDRESS] -C 5 -K 1 -a [VICTIM DEFAULT GW IP ADDRESS] --icmp-gw [ATTACKER IP ADDRESS] --icmp-ipdst [DST IP ADDRESS] --icmp-ipsrc [VICTIM IP ADDRESS] #Send icmp to [1] form [2], route to [3] packets sent to [4] from [5]
set dns.spoof.hosts ./dns.spoof.hosts; dns.spoof on
```
**Configure own DNS with dnsmasq**
```bash
apt-get install dnsmasqecho "addn-hosts=dnsmasq.hosts" > dnsmasq.conf #Create dnsmasq.confecho "127.0.0.1 domain.example.com" > dnsmasq.hosts #Domains in dnsmasq.hosts will be the domains resolved by the Dsudo dnsmasq -C dnsmasq.conf --no-daemon
dig @localhost domain.example.com # Test the configured DNS
Multiple routes to systems and networks often exist. Upon building a list of MAC addresses within the local network, use _gateway-finder.py_ to identify hosts that support IPv4 forwarding.
Microsoft systems use Link-Local Multicast Name Resolution (LLMNR) and the NetBIOS Name Service (NBT-NS) for local host resolution when DNS lookups fail. Apple Bonjour and Linux zero-configuration implementations use Multicast DNS (mDNS) to discover systems within a network. These protocols are unauthenticated and broadcast messages over UDP; thus, attackers can exploit them to direct users to malicious services.
Many browsers use Web Proxy Auto-Discovery (WPAD) to load proxy settings from the network. A WPAD server provides client proxy settings via a particular URL (e.g., [http://wpad.example.org/wpad.dat](http://wpad.example.org/wpad.dat)) upon being identified through any of the following:
* DHCP, using a code 252 entry[34](https://learning.oreilly.com/library/view/Network+Security+Assessment,+3rd+Edition/9781491911044/ch05.html#ch05fn41)
* DNS, searching for the _wpad_ hostname in the local domain
You can offer different services in the network to try to **trick a user** to enter some **plain-text credentials**. **More information about this attack in** [**Spoofing SSDP and UPnP Devices**](spoofing-ssdp-and-upnp-devices.md)**.**
By default some OS try to configure the DNS reading a DHCPv6 packet in the network. Then, an attacker could send a DHCPv6 packet to configure himself as DNS. The DHCP also provides an IPv6 to the victim.
Basically what this attack does is, in case the **user** try to **access** a **HTTP** page that is **redirecting** to the **HTTPS** version. **sslStrip** will **maintain** a **HTTP connection with** the **client and** a **HTTPS connection with** the **server** so it ill be able to **sniff** the connection in **plain text**.
```bash
apt-get install sslstrip
sslstrip -w /tmp/sslstrip.log --all - l 10000 -f -k
The **difference** between **sslStrip+ and dns2proxy** against **sslStrip** is that they will **redirect** for example _**www.facebook.com**_**to**_**wwww.facebook.com**_ (note the **extra** "**w**") and will set the **address of this domain as the attacker IP**. This way, the **client** will **connect** to _**wwww.facebook.com**_**(the attacker)** but behind the scenes **sslstrip+** will **maintain** the **real connection** via https with **www.facebook.com**.
The **goal** of this technique is to **avoid HSTS** because _**wwww**.facebook.com_**won't** be saved in the **cache** of the browser, so the browser will be tricked to perform **facebook authentication in HTTP**.\
Note that in order to perform this attack the victim has to try to access initially to [http://www.faceook.com](http://www.faceook.com) and not https. This can be done modifying the links inside an http page.
More info [here](https://www.bettercap.org/legacy/#hsts-bypass), [here](https://www.slideshare.net/Fatuo\_\_/offensive-exploiting-dns-servers-changes-blackhat-asia-2014) and [here](https://security.stackexchange.com/questions/91092/how-does-bypassing-hsts-with-sslstrip-work-exactly).
**sslStrip or sslStrip+ doesn;t work anymore. This is because there are HSTS rules presaved in the browsers, so even if it's the first time that a user access an "important" domain he will access it via HTTPS. Also, notice that the presaved rules and other generated rules can use the flag** [**`includeSubdomains`**](https://hstspreload.appspot.com) **so the**_**wwww.facebook.com**_**example from before won't work anymore as**_**facebook.com**_**uses HSTS with `includeSubdomains`.**
Other things to test is to try to sign the certificate with a valid certificate that it is not a valid CA. Or to use the valid public key, force to use an algorithm as diffie hellman (one that do not need to decrypt anything with the real private key) and when the client request a probe of the real private key (like a hash) send a fake probe and expect that the client does not check this.
ARP packets are used to discover wich IPs are being used inside the network. The PC has to send a request for each possible IP address and only the ones that are being used will respond.
Bettercap send a MDNS request (each X ms) asking for **\_services\_.dns-sd.\_udp.local** the machine that see this paket usually answer this request. Then, it only searchs for machine answering to "services".
**Bug bounty tip**: **sign up** for **Intigriti**, a premium **bug bounty platform created by hackers, for hackers**! Join us at [**https://go.intigriti.com/hacktricks**](https://go.intigriti.com/hacktricks) today, and start earning bounties up to **$100,000**!
- Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
- **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
