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https://github.com/redteampentesting/pretender

Your MitM sidekick for relaying attacks featuring DHCPv6 DNS takeover as well as mDNS, LLMNR and NetBIOS-NS spoofing.
https://github.com/redteampentesting/pretender

dhcpv6 dns go llmnr mdns netbios pentesting pretender relaying security spoofer

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Your MitM sidekick for relaying attacks featuring DHCPv6 DNS takeover as well as mDNS, LLMNR and NetBIOS-NS spoofing.

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pretender


  
Your MitM sidekick for relaying attacks featuring DHCPv6 DNS takeover
as well as mDNS, LLMNR and NetBIOS-NS spoofing


  


    Release

    GitHub Action: Check

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    Go Report Card

  



---



`pretender` is a tool developed by RedTeam Pentesting to obtain

machine-in-the-middle positions via spoofed local name resolution and DHCPv6 DNS

takeover attacks. `pretender` primarily targets Windows hosts, as it is intended

to be used for relaying attacks but can be deployed on Linux, Windows and all

other platforms Go supports. Name resolution queries can be answered with

arbitrary IPs for situations where the relaying tool runs on a different host

than `pretender`. It is designed to work with tools such as

[Impacket's](https://github.com/SecureAuthCorp/impacket) `ntlmrelayx.py` and

[krbrelayx](https://github.com/dirkjanm/krbrelayx) that handle the incoming

connections for relaying attacks or hash dumping.



Read our [blog

post](https://blog.redteam-pentesting.de/2022/introducing-pretender/) for more

information about DHCPv6 DNS takeover, local name resolution spoofing and relay

attacks.



---



## Usage



To get a feel for the situation in the local network, `pretender` can be started

in `--dry` mode where it only logs incoming queries and does not answer any of

them:



```sh

pretender -i eth0 --dry

pretender -i eth0 --dry --no-ra # without router advertisements (RA)

pretender -i eth0 --dry --no-ra-dns # with RA but without advertizing DNS in RA

```



To perform local name resolution spoofing via mDNS, LLMNR and NetBIOS-NS as well

as a DHCPv6 DNS takeover with router advertisements, simply run `pretender` like

this:



```sh

pretender -i eth0

```



You can disable certain attacks with `--no-dhcp-dns` (disabled DHCPv6, DNS and

router advertisements), `--no-lnr` (disabled mDNS, LLMNR and NetBIOS-NS),

`--no-mdns`, `--no-llmnr`, `--no-netbios` and `--no-ra`.



If `ntlmrelayx.py` runs on a different host (say `10.0.0.10`/`fe80::5`), run

`pretender` like this:



```sh

pretender -i eth0 -4 "10.0.0.10" -6 "fe80::5"

```



Pretender can be setup to only respond to queries for certain domains (or all

_but_ certain domains) and it can perform the spoofing attacks only for certain

hosts (or all _but_ certain hosts). Referencing hosts by hostname relies on the

name resolution of the host that runs `pretender`. See the following example:



```sh

pretender -i eth0 --spoof "example.com" --dont-spoof-for "10.0.0.3,host1.corp,fe80::f" --ignore-nofqdn

```



For more information, run `pretender --help`.



---



## Tips



- Make sure to enable IPv6 support in `ntlmrelayx.py` with the `-6` flag.

- Pretender supports stateless DNS configuration via Router Advertisements

  without DHCPv6 with the `--stateless-ra` flag. By default, the DHCPv6 server

  is still started but it can be disabled using `--no-dhcp`.

- If `--dont-spoof`/`--dont-spoof-for` filters are present and no upstream DNS

  server is configured with `--delegate-ignored-to`, router advertisements will

  not directly advertize the DNS server which makes the attack less effective.

- Pretender can be configured to stop after a certain time period for situations

  where it cannot be aborted manually (`--stop-after` and

  `main.vendorStopAfter`).

- Host info lookup (which relies on the ARP table, IP neighbours and reverse

  lookups) can be disabled with `--no-host-info` or `main.vendorNoHostInfo`

- If you are not sure which interface to choose (especially on Windows), list

  all interfaces with names and addresses using `--interfaces`.

- If you want to exclude hosts from local name resolution spoofing, make sure to

  also exclude their IPv6 addresses or use

  `--no-ipv6-lnr`/`main.vendorNoIPv6LNR`.

- DHCPv6 messages usually contain a FQDN option (which can also sometimes

  contain a hostname which is not a FQDN). This option is used to filter out

  messages by hostname (`--spoof-for`/`--dont-spoof-for`). You can decide what

  to do with DHCPv6 messages without FQDN option by setting or omitting

  `--ignore-nofqdn`.

- Depending on the build configuration, either the operating system resolver

  (`CGO_ENABLED=1`) or a Go implementation (`CGO_ENABLED=0`) is used. This can

  be important for host info collection because the OS resolver may support

  local name resolution and the Go implementation does not, unless a stub

  resolver is used..

- The host info functionality is currently only available for Windows and Linux.

- A custom MAC address vendor list can be compiled into the binary by replacing

  the default list `hostinfo/mac-vendors.txt`. Only lines with MAC prefixes in

  the following format are recognized: `FF:FF:FFVendorIDVendor` (the

  MAC prefix length can be arbitrary).

- If you only want to perform Kerberos relaying you can specify `--no-lnr` and

  `--spoof-types SOA` to ignore any queries that are unrelated to the attack.

- When conducting a Kerberos relay attack where `krbrelayx.py` runs on a

  different host than pretender (relay IPv4 address points to different host

  that runs `krbrelayx.py`), the host running `krbrelayx.py` will also need to

  run pretender in order to receive and deny the Dynamic Update query sent to

  the relay IPv4 address.

- By default, in order to limit disruption during a DHCPv6 DNS Takeover, the

  option `--delegate-ignored-to ` can be used to delegate ignored

  queries to a legitimate DNS server.

- The option `--dry-with-dhcp` can be combined with `--delegate-ignored-to` to

  monitor the name resolution queries in the network without disruption.

---



## Building and Vendoring



Pretender can be build as follows:



```sh

go build

```



Pretender can also be compiled with pre-configured settings. For this, the

`ldflags` have to be modified like this:



```sh

-ldflags '-X main.vendorInterface=eth1'

```



For example, Pretender can be built for Windows with a specific default

interface, without colored output and with a relay IPv4 address configured:



```

GOOS=windows go build -trimpath -ldflags '-X "main.vendorInterface=Ethernet 2" -X main.vendorNoColor=true -X main.vendorRelayIPv4=10.0.0.10'

```



Full list of vendoring options (see `defaults.go` or `pretender --help` for

detailed information):



```

vendorInterface

vendorRelayIPv4

vendorRelayIPv6

vendorSOAHostname

vendorNoDHCPv6DNSTakeover

vendorNoDHCPv6

vendorNoDNS

vendorNoMDNS

vendorNoNetBIOS

vendorNoLLMNR

vendorNoLocalNameResolution

vendorNoIPv6LNR

vendorNoRA

vendorNoRADNS

vendorSpoof

vendorDontSpoof

vendorSpoofFor

vendorDontSpoofFor

vendorSpoofTypes

vendorIgnoreDHCPv6NoFQDN

vendorDelegateIgnoredTo

vendorDontSendEmptyReplies

vendorDryMode

vendorDryWithDHCPMode

vendorStatelessRA

vendorTTL

vendorLeaseLifetime

vendorRARouterLifetime

vendorRAPeriod

vendorDNSTimeout

vendorStopAfter

vendorVerbose

vendorNoColor

vendorNoTimestamps

vendorLogFileName

vendorNoHostInfo

vendorHideIgnored

vendorRedirectStderr

vendorListInterfaces

```