atomic-red-team/atomics/T1071/T1071.md

T1071 - Standard Application Layer Protocol

Description from ATT&CK

Adversaries may communicate using a common, standardized application layer protocol such as HTTP, HTTPS, SMTP, or DNS to avoid detection by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server.

For connections that occur internally within an enclave (such as those between a proxy or pivot node and other nodes), commonly used protocols are RPC, SSH, or RDP.

Atomic Tests

• Atomic Test #1 - Malicious User Agents

• Atomic Test #2 - Malicious User Agents - Nix

• Atomic Test #3 - DNS Large Query Volume

• Atomic Test #4 - DNS Regular Beaconing

• Atomic Test #5 - DNS Long Domain Query

Atomic Test #1 - Malicious User Agents

This test simulates an infected host beaconing to command and control. Inspired by APTSimulator - https://github.com/NextronSystems/APTSimulator/blob/master/test-sets/command-and-control/malicious-user-agents.bat

Supported Platforms: Windows

Inputs

Name	Description	Type	Default Value
domain	Default domain to simulate against	string	www.google.com

Run it with powershell!

Invoke-WebRequest #{domain} -UserAgent "HttpBrowser/1.0" | out-null
Invoke-WebRequest #{domain} -UserAgent "Wget/1.9+cvs-stable (Red Hat modified)" | out-null
Invoke-WebRequest #{domain} -UserAgent "Opera/8.81 (Windows NT 6.0; U; en)" | out-null
Invoke-WebRequest #{domain} -UserAgent "*<|>*" | out-null

Atomic Test #2 - Malicious User Agents - Nix

This test simulates an infected host beaconing to command and control. Inspired by APTSimulator - https://github.com/NextronSystems/APTSimulator/blob/master/test-sets/command-and-control/malicious-user-agents.bat

Supported Platforms: Linux, macOS

Inputs

Name	Description	Type	Default Value
domain	Default domain to simulate against	string	www.google.com

Run it with sh!

curl -s -A "HttpBrowser/1.0" -m3 #{domain}
curl -s -A "Wget/1.9+cvs-stable (Red Hat modified)" -m3 #{domain}
curl -s -A "Opera/8.81 (Windows NT 6.0; U; en)" -m3 #{domain}
curl -s -A "*<|>*" -m3 #{domain}

Atomic Test #3 - DNS Large Query Volume

This test simulates an infected host sending a large volume of DNS queries to a command and control server. The intent of this test is to trigger threshold based detection on the number of DNS queries either from a single source system or to a single targe domain.

Supported Platforms: Windows

Inputs

Name	Description	Type	Default Value
domain	Default domain to simulate against	string	example.com
subdomain	Subdomain prepended to the domain name	string	atomicredteam
query_type	DNS query type	string	TXT
query_volume	Number of DNS queries to send	integer	1000

Run it with powershell!

for($i=0; $i -le #{query_volume}; $i++) { Resolve-DnsName -type "#{query_type}" "#{subdomain}.$(Get-Random -Minimum 1 -Maximum 999999).#{domain}" -QuickTimeout}

Atomic Test #4 - DNS Regular Beaconing

This test simulates an infected host beaconing via DNS queries to a command and control server at regular intervals over time. This behaviour is typical of implants either in an idle state waiting for instructions or configured to use a low query volume over time to evade threshold based detection.

Supported Platforms: Windows

Inputs

Name	Description	Type	Default Value
domain	Default domain to simulate against	string	example.com
subdomain	Subdomain prepended to the domain name	string	atomicredteam
query_type	DNS query type	string	TXT
c2_interval	Seconds between C2 requests to the command and control server	integer	30
c2_jitter	Percentage of jitter to add to the C2 interval to create variance in the times between C2 requests	integer	20
runtime	Time in minutes to run the simulation	integer	30

Run it with powershell!

.\T1071-dns-beacon.ps1 -Domain #{domain} -Subdomain #{subdomain} -QueryType #{query_type} -C2Interval #{c2_interval} -C2Jitter #{c2_jitter} -RunTime #{runtime}

Atomic Test #5 - DNS Long Domain Query

This test simulates an infected host returning data to a command and control server using long domain names. The simulation involves sending DNS queries that gradually increase in length until reaching the maximum length. The intent is to test the effectiveness of detection of DNS queries for long domain names over a set threshold.

Supported Platforms: Windows

Inputs

Name	Description	Type	Default Value
domain	Default domain to simulate against	string	example.com
subdomain	Subdomain prepended to the domain name (should be 63 characters to test maximum length)	string	atomicredteamatomicredteamatomicredteamatomicredteamatomicredte
query_type	DNS query type	string	TXT

Run it with powershell!

.\T1071-dns-domain-length.ps1 -Domain #{domain} -Subdomain #{subdomain} -QueryType #{query_type}