Find potential privilege escalation with defined services. STIG VID's; V-906, V-907, V-910, V-4089, V-4090, V-4091, V-22354, V-22355, V-59827, V-59831, V-59833, V-59835, V-59837, V-59839, V-59841, V-59843

stig.sh

#!/bin/bash

# Handle the following STIG Vulnerability ID's
# Requires bash > v4
#  HP-UX: V-906, V-907, V-910, V-4089, V-4090, V-4091, V-22354, V-22355
#  OEL: V-906, V-907, V-910, V-4089, V-4090, V-4091, V-22354, V-22355
#  RHEL: V-906, V-907, V-910, V-4089, V-4090, V-4091, V-22354, V-22355
#  Solaris: V-906, V-907, V-910, V-4089, V-4090, V-4091, V-22354, V-22355, V-59827, V-59831, V-59833, V-59835, V-59837, V-59839, V-59841, V-59843

# Author: Jason Gerfen <jason.gerfen@gmail.com>
# License: MIT

# Define start service(s)
declare -a inits
inits+=("/etc/rc*")                # init.d
inits+=("/etc/init*")              # xinit.d
inits+=("/lib/svc")                # Solaris SMF
inits+=("/usr/lib/systemd/system") # RHL systemd


# Array of allowed owners
declare -a allowed
allowed+=("root")
allowed+=("sys")
allowed+=("bin")

# Minimum octal mode for permissions
perm=00750

# File extraction pattern
pattern="[/\|~\|..][a-z0-9A-Z._-]*"


# Ensure path is robust
PATH=$PATH:/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin

# Set awk to nawk if Solaris
if [ $(uname -a | grep -c SunOS) -ne 0 ]; then
  nawk="$(which nawk 2>/dev/null)"
else
  nawk="$(which awk 2>/dev/null)"
fi


# Resolve symlinks to a file
# FIX: Needs to handle recursion for non readlink systems
function get_inode()
{
  # Copy ${1} to a local variable
  local inode="${1}"

  # If ${file} is a link
  if [[ -h ${inode} ]] || [[ -L ${inode} ]]; then

    # Attempt to follow link where readlink is available
    [ $(which readlink | grep -c "^/") -gt 0 ] &&
      inode="$(readlink -f ${inode} 2>/dev/null)"
  fi

  echo "${inode}" && return 0
}


# Pluck *possible* file(s) from a file based on ${pattern}
function extract_filenames()
{
  local file="${1}"
  local iterations=10 # This will search up to 10 paths deep

  local -a results=()
  local tpat=
  local i=0

  # Iterate 0 - ${iterations}
  #for i in $(seq 1 ${iterations}); do
  while [ ${i} -le ${iterations} ]; do

    # Combine ${tpat} with ${pattern} to account for BRE limitations with complex regex's
    tpat="${tpat}${pattern}"

    # Combine the ${prefix}, ${tpat} & ${suffix} for a complete regex
    pat="${prefix}${tpat}${suffix}"

    # Extract any patterns matching ${pat} from ${file} while assigning to ${tresults[@]}
    results+=($(sed -ne "s|.*\(${pat}\).*|\1|p" ${file} 2> /dev/null))

    # Increment ${i}
    i=$(( ${i} + 1 ))
  done

  # Provide the ${results[@]} if > 0
  [ ${#results[@]} -gt 0 ] && echo "${results[@]}" | tr ' ' '\n' | sort -u | tr '\n' ' '
}


# Strip out dupes from provided array
function remove_duplicates()
{
  local -a obj
  obj=("${@}")

  echo "${obj[@]}" | tr ' ' '\n' | sort -u | tr '\n' ' '
}


# Test for actual files & non-binaries
function test_file()
{
  # Reassign ${@}
  local -a obj="${@}"
  local -a results

  # Iterate ${obj[@]}
  for inode in ${obj[@]}; do

    # Filter for valid file(s) & assign to ${results[@]}
    [ -f ${inode} ] && results+=(${inode})
  done

  echo "${results[@]}"
}


# Is ELF or data file?
function is_compiled()
{
  echo $(file ${1} | egrep -c 'ELF|data')
}


# Perform search of array
function in_array()
{
  local args=("${@}")
  local needle="${args[0]}"
  local haystack=("${args[@]:1}")

  for i in ${haystack[@]}; do
    if [[ ${i} == ${needle} ]]; then
      echo 0 && return 0
    fi
  done

  echo 1 && return 1
}


# Get current owner
function get_inode_user()
{
  local inode="${1}"

  echo "$(ls -lad ${inode} | awk '{print $3}')" && return 0
}


# Get current group ownership
function get_inode_group()
{
  local inode="${1}"

  echo "$(ls -lad ${inode} | awk '{print $4}')" && return 0
}


# Resolve the current permission (non POSIX compat)
function get_octal()
{
  local inode="${1}"

  # Verify ${inode} exists
  if [[ ! -d ${inode} ]] && [[ ! -f ${inode} ]]; then
    return 1
  fi

  echo $(ls -lahd ${inode} | ${nawk} '{k = 0; for (g=2; g>=0; g--) for (p=2; p>=0; p--) {c = substr($1, 10 - (g * 3 + p), 1); if (c ~ /[sS]/) k += g * 02000; else if (c ~ /[tT]/) k += 01000; if (c ~ /[rwxts]/) k += 8^g * 2^p} if (k) printf("%05o", k)}')

  return 0
}


# Get list of init scripts to examine
files=( $(find ${inits[@]} -type f -ls | awk '{print $11}') )


# Iterate ${files[@]}, resolve to actual file and pluck possible file(s) for examination
for inode in ${files[@]}; do

  # Handle symlinks
  inode="$(get_inode ${inode})"

  # Skip stripping out possible files from ELF's & data files
  if [ $(is_compiled ${inode}) -gt 0 ]; then
    tmp_files+=("${inode}")
    continue
  fi

  # Use extract_filenames() to obtain array of binaries from ${inode}
  tmp_files+=( $(extract_filenames ${inode}) )
done


# Remove dupes
files=( ${files[@]} $(remove_duplicates "${tmp_files[@]}") )


# Filter for actual files
files=( $(test_file "${files[@]}") )


# Iterate ${files[@]} and create haystack to find
for inode in ${files[@]}; do

  # Bail if ${inode} is null
  [ "${inode}" == "" ] && continue

  # Handle symlinks
  inode="$(get_inode ${inode})"

  # Bail if ${inode} is null
  [ "${inode}" == "" ] && continue


  # Get current owner & group
  owner="$(get_inode_user ${inode})"
  group="$(get_inode_group ${inode})"
  perms=$(get_octal ${inode})

  # If ${perms}, ${owner} or ${group} of ${inode} doesn't existin in ${allowed[@]} or minimum octal notation flag it
  [ $(in_array ${owner} ${allowed[@]}) -ne 0 ] && perms+=("${inode}") || vals+=("${inode}")
  [ $(in_array ${group} ${allowed[@]}) -ne 0 ] && perms+=("${inode}") || vals+=("${inode}")
  [ ${perms} -gt ${perm} ] && perms+=("${inode}") || vals+=("${inode}")


  # Skip creating a haystack from ${inode} if is_binary is < 0
  [ $(is_compiled ${inode}) -gt 0 ] && continue

  # Extract possible PATH|LD_LIBRARY_PATH|LD_PRELOAD from ${inode} to an array as ${haystack[@]}
  haystack=( $(${nawk} '$0 ~ /LD_LIBRARY_PATH|PATH|LD_PRELOAD=/{if ($0 ~ /LD_LIBRARY_PATH|PATH|LD_PRELOAD=/){split($0, obj, "=");if(obj[2] ~ /;/){split(obj[2], fin, ";")}else{fin[2]=obj[2]}print fin[2]}}' ${inode} 2>/dev/null) )

  # Skip ${inode} if PATH not found
  [ ${#haystack[@]} -eq 0 ] && continue


  # Iterate ${haystack[@]}
  for haybail in ${haystack[@]}; do

    # Examine ${haybail} for invalid path
    #  TODO: An eval() might be good here to accommodate for possible variables in ${haybail}
    chk=$(echo "${haybail}" | egrep -c '^:|::|:$|:[a-zA-Z0-9-_~.]+')

    # Add ${inode} to ${errs[@]} array if ${chk} > 0 OR add it to ${vals[@]} array
    [ ${chk} -gt 0 ] && errs+=("${inode}") || vals+=("${inode}")
  done
done


# Remove dupes
perms=($(remove_duplicates ${perms[@]}))
errs=($(remove_duplicates ${errs[@]}))
vals=($(remove_duplicates ${vals[@]}))


# Print what was examined and what failed
cat <<EOF
Errors (permissions/ownership): ${#perms[@]}/${#files[@]}
${perms[@]}

Errors (LD_LIBRARY_PATH/PATH/LD_PRELOAD): ${#errs[@]}/${#files[@]}
${errs[@]}

Validated: ${#vals[@]}/${#files[@]}
${vals[@]}
EOF