Metasploit Module: Reliable Datagram Sockets (RDS) rds_atomic_free_op NULL pointer dereference Privilege Escalation
Type: exploit
Path: modules/exploits/linux/local/rds_atomic_free_op_null_pointer_deref_priv_esc.rb
Disclosure date: 2018-11-01
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=7d11f77f84b27cef452cee332f4e[PII_REDACTED]37, 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

Description:
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.

Check method (fingerprinting):
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("Kernel version #{version} appears to be vulnerable")
  end