Procedure examples

TrickBot can use secondary C2 servers for communication after establishing connectivity and relaying victim information to primary C2 servers.

Bumblebee can use backup C2 servers if the primary server fails.

Stuxnet has the ability to generate new C2 domains.

Exaramel for Linux can attempt to find a new C2 server if it receives an error.

WinMM is usually configured with primary and backup domains for C2 communications.

RainyDay has the ability to switch between TCP and HTTP for C2 if one method is not working.

AppleSeed can use a second channel for C2 when the primary channel is in upload mode.

TinyTurla can go through a list of C2 server IPs and will try to register with each until one responds.

SslMM has a hard-coded primary and backup C2 string.

Machete has sent data over HTTP if FTP failed, and has also used a fallback server.

HOPLIGHT has multiple C2 channels in place in case one fails.

InvisiMole has been configured with several servers available for alternate C2 communications.

QUIETEXIT can attempt to connect to a second hard-coded C2 if the first hard-coded C2 address fails.

RDAT has used HTTP if DNS C2 communications were not functioning.

Kazuar can accept multiple URLs for C2 servers.

NETEAGLE will attempt to detect if the infected host is configured to a proxy. If so, NETEAGLE will send beacons via an HTTP POST request; otherwise it will send beacons via UDP/6000.

FatDuke has used several C2 servers per targeted organization.

BlackEnergy has the capability to communicate over a backup channel via plus.google.com.

ShimRat has used a secondary C2 location if the first was unavailable.

MiniDuke uses Google Search to identify C2 servers if its primary C2 method via Twitter is not working.

Anchor can use secondary C2 servers for communication after establishing connectivity and relaying victim information to primary C2 servers.

S-Type primarily uses port 80 for C2, but falls back to ports 443 or 8080 if initial communication fails.

DustySky has two hard-coded domains for C2 servers; if the first does not respond, it will try the second.

The C2 server used by XTunnel provides a port number to the victim to use as a fallback in case the connection closes on the currently used port.

CharmPower can change its C2 channel once every 360 loops by retrieving a new domain from the actors’ S3 bucket.

QUADAGENT uses multiple protocols (HTTPS, HTTP, DNS) for its C2 server as fallback channels if communication with one is unsuccessful.

TAINTEDSCRIBE can randomly pick one of five hard-coded IP addresses for C2 communication; if one of the IP fails, it will wait 60 seconds and then try another IP address.

GlassWorm has utilized Google Calendar as backup C2.

Uroburos can use up to 10 channels to communicate between implants.

PipeMon can switch to an alternate C2 domain when a particular date has been reached.

JHUHUGIT tests if it can reach its C2 server by first attempting a direct connection, and if it fails, obtaining proxy settings and sending the connection through a proxy, and finally injecting code into a running browser if the proxy method fails.

Crutch has used a hardcoded GitHub repository as a fallback channel.

Derusbi uses a backup communication method with an HTTP beacon.

Shark can update its configuration to use a different C2 server.

Bazar has the ability to use an alternative C2 server if the primary server fails.

HiddenFace can use active and passive C2 modes that use different encryption algorithms and backdoor commands.

Valak can communicate over multiple C2 hosts.

OilBooster can use a backup channel to request a new refresh token from its C2 server after 10 consecutive unsuccessful connections to the primary OneDrive C2 server.

Cardinal RAT can communicate over multiple C2 host and port combinations.

BISCUIT malware contains a secondary fallback command and control server that is contacted after the primary command and control server.

Kwampirs uses a large list of C2 servers that it cycles through until a successful connection is established.

CHOPSTICK can switch to a new C2 channel if the current one is broken.

Ebury has implemented a fallback mechanism to begin using a DGA when the attacker hasn't connected to the infected system for three days.

SideTwist has primarily used port 443 for C2 but can use port 80 as a fallback.

Mis-Type first attempts to use a Base64-encoded network protocol over a raw TCP socket for C2, and if that method fails, falls back to a secondary HTTP-based protocol to communicate to an alternate C2 server.

Kevin can assign hard-coded fallback domains for C2.

Linfo creates a backdoor through which remote attackers can change C2 servers.

Gelsemium can use multiple domains and protocols in C2.

Mythic can use a list of C2 URLs as fallback mechanisms in case one IP or domain gets blocked.

TeamPCP Cloud Stealer can compress and encrypt data and exfiltrate it via POST to an attacker-controlled domain. If that method fails it can use the victim's own GitHub account to create a public repository and uploads the encrypted data as a release asset.