#!/bin/bash
# 02-02-2022  CVE-2021-44142
# Enrico Pasqualotto epasqualotto AT backloop.biz
# run with --fix for auto-fix option

OS_DETECTED=0
fix=0
declare -A fixedVer
declare -A vulnVer

function vercomp () {
    if [[ $1 == $2 ]]
    then
        return 0
    fi
    local IFS=.
    local i ver1=($1) ver2=($2)
    # fill empty fields in ver1 with zeros
    for ((i=${#ver1[@]}; i<${#ver2[@]}; i++))
    do
        ver1[i]=0
    done
    for ((i=0; i<${#ver1[@]}; i++))
    do
        if [[ -z ${ver2[i]} ]]
        then
            # fill empty fields in ver2 with zeros
            ver2[i]=0
        fi
        if ((10#${ver1[i]} > 10#${ver2[i]}))
        then
            return 1
        fi
        if ((10#${ver1[i]} < 10#${ver2[i]}))
        then
            return 2
        fi
    done
    return 0
}

function getDebianPkgVer (){

        pkgver=`dpkg -s "$1" | grep Version | cut -d ":" -f2-| cut -d' ' -f2`
        echo $pkgver

}

if [ "$1" == "--help" ]; then
	echo "Use --fix to patch your system"
	exit 0
elif [ "$1" == "--fix" ]; then
	fix=1
	echo "Run with auto-fix enabled!"
	sleep 2
fi


#OS CHECK

if [[ "$OSTYPE" != "linux-gnu"* ]]; then
	echo "O.S. $OSTYPE Not supported!"
	exit 1
fi

#ubuntu
if [ -f /etc/os-release ]; then
	TMP_DISTRIB=`cat /etc/os-release | grep -m1 "^NAME" | cut -d "=" -f2 | sed s/\"//g`

	if [ "$TMP_DISTRIB" == "Ubuntu" ]; then

		OS_DETECTED=1

		DISTRIB=`cat /etc/os-release | grep -m1 "^NAME" | cut -d "=" -f2 | sed s/\"//g`
	        VERNAME=`cat /etc/os-release | grep -m1 "VERSION_CODENAME" | cut -d "=" -f2`
        	VER=`cat /etc/os-release | grep -m1 "VERSION_ID" | cut -d "=" -f2 | sed s/\"//g`

		echo "Detected O.S. : $DISTRIB $VER $VERNAME"
	fi
fi

# debian
if [ "$OS_DETECTED" == "0" ] && [ -f /etc/debian_version ]; then

        OS_DETECTED=1

	VER=`cat /etc/debian_version`
	DISTRIB=Debian
        VERNAME=$(. /etc/os-release && echo ${VERSION_CODENAME-stretch})

	echo "Detected O.S. : $DISTRIB $VER $VERNAME"

fi

# redhat
if [ "$OS_DETECTED" == "0" ] && [ -f /etc/redhat-release ]; then

	OS_DETECTED=1
        DISTRIB=`cat /etc/os-release | grep -m1 "^NAME" | cut -d "=" -f2 | sed s/\"//g`
        VERNAME=`cat /etc/os-release | grep -m1 "PRETTY_NAME" | cut -d "=" -f2`
        VER=`cat /etc/os-release | grep -m1 "VERSION_ID" | cut -d "=" -f2 | sed s/\"//g`

        echo "Detected O.S. : $DISTRIB $VER $VERNAME"
fi


if [ "$OS_DETECTED" == "0" ]; then
	echo "O.S. not supported!"
	exit 1
fi
#cat /etc/os-release | grep -m1 "NAME" | cut -d "=" -f2 | sed s/\"//g


if [ "$DISTRIB" == "Ubuntu" ]; then

	PACKAGE=samba
	
	fixedVer["1804"]="2:4.7.6+dfsg~ubuntu-0ubuntu2.28"
	fixedVer["2004"]="2:4.13.17~dfsg-0ubuntu0.21.04.1"
	fixedVer["2110"]="2:4.13.17~dfsg-0ubuntu0.21.10.1"

	isinstalled=`dpkg -l | grep $PACKAGE | wc -l`

        if [ "$isinstalled" == "0" ]; then
                echo "No package found on your system. You are not vulnerable!"
                exit 0
	fi

	curver=`getDebianPkgVer "$PACKAGE"`
	#echo $curver
	#echo ${fixedVer[`echo $VER| sed 's/\.//'`]}

	if [ "${fixedVer[`echo $VER| sed 's/\.//'`]}" == "" ]; then
		echo "No patch available for your distribution/version"
		//echo "Try mitigate with command: chmod 0755 /usr/bin/pkexec"
		exit 1
	fi

	if [ "$curver" == "${fixedVer[`echo $VER| sed 's/\.//'`]}" ]; then
		res='same'
		vuln=0
	else
		dpkg --compare-versions $curver lt ${fixedVer[`echo $VER| sed 's/\.//'`]}
		cmpres=$?
		case $cmpres in
        		0) 
				res='lower'
				vuln=1
				;;
	        	1) 
				res='greater'
				vuln=0
				;;
		esac
	fi
	echo "My version ($curver) is $res than version (${fixedVer[`echo $VER| sed 's/\.//'`]}) with the patch"
	if [ "$vuln" == "0" ]; then
		echo "System not vulnerable"
	else
		echo "System vulnerable!"

		if [ "$fix" == "1" ]; then
		
			isroot=`id -u`
			if [ "$isroot" != "0" ]; then
				echo "Auto-fix option need root privildge. Please run with sudo or as root"
				exit 1
			fi
			
			apt-get update
			apt-get -y install $PACKAGE

			newver=`getDebianPkgVer "$PACKAGE"`
			
			if [ "$curver" != "$newver" ]; then
				echo "Upgrade done"
				dpkg --compare-versions $newver lt ${fixedVer[`echo $VER| sed 's/\.//'`]}
		                cmpres=$?
                		case $cmpres in
		                        0) 
       		                        	res='lower'
               		                	vuln=1
                       		        ;;
                        		1) 
                                		res='greater'
                                		vuln=0
                                	;;
                		esac
        		
				echo "My version ($newver) is $res than version (${fixedVer[`echo $VER| sed 's/\.//'`]}) with the patch"
				echo "System no more vulnerable!"
			else
				echo "Attempt to install new version of pkg failed!"
			fi
		fi
	fi


elif [ "$DISTRIB" == "Debian" ]; then
		
		PACKAGE=samba
		
        vulnVer["stretch"]="2:4.5.16+dfsg-1+deb9u4"
		vulnVer["buster"]="2:4.9.5+dfsg-5+deb10u2"
		vulnVer["bulleye"]="2:4.13.13+dfsg-1~deb11u2"
		vulnVer["sid"]="2:4.13.14+dfsg-1"
		vulnVer["bookworm"]="2:4.13.14+dfsg-1"

        isinstalled=`dpkg -l | grep $PACKAGE | wc -l`

        if [ "$isinstalled" == "0" ]; then
                echo "No package found on your system. You are not vulnerable!"
                exit 0
        fi

        curver=`getDebianPkgVer "$PACKAGE"`
        #echo $curver
        #echo ${fixedVer[$VERNAME]}

		myvulnver=${vulnVer[`echo $VERNAME| sed 's/\.//'`]}
		myfixedver=${fixedVer[`echo $VERNAME| sed 's/\.//'`]}
		
		if [ "$myvulnver" == "" ] && [ "$myfixedver" == "" ]; then  
		
			echo "No information available for your system. Sorry"
            exit 0
            
        elif [ "$myfixedver" != "" ]; then  
        
			if [ "$curver" == "$myfixedver" ]; then
				res='same'
				vuln=0
			else
				dpkg --compare-versions $curver lt $myfixedver
				cmpres=$?
				case $cmpres in
						0) 
						res='lower'
						vuln=1
						;;
						1) 
						res='greater'
						vuln=0
						;;
				esac
			fi
			echo "My version ($curver) is $res than version ($myfixedver) with the patch"
			if [ "$vuln" == "0" ]; then
				echo "System not vulnerable"
			else
				echo "System vulnerable!"

				if [ "$fix" == "1" ]; then
				
					isroot=`id -u`
					if [ "$isroot" != "0" ]; then
						echo "Auto-fix option need root privildge. Please run with sudo or as root"
						exit 1
					fi
					
					apt-get update
					apt-get -y install $PACKAGE

					newver=`getDebianPkgVer "$PACKAGE"`
					
					if [ "$curver" != "$newver" ]; then
						echo "Upgrade done"
						dpkg --compare-versions $newver lt $myfixedver
								cmpres=$?
								case $cmpres in
										0) 
												res='lower'
												vuln=1
											;;
										1) 
												res='greater'
												vuln=0
											;;
								esac
						
						echo "My version ($newver) is $res than version ($myfixedver) with the patch"
						echo "System no more vulnerable!"
					else
						echo "Attempt to install new version of pkg failed!"
					fi
				fi
			fi

        
        elif [ "$myvulnver" != "" ]; then  
              
			if [ "$curver" == "$myvulnver" ]; then
				res='same'
				vuln=1
			else
				dpkg --compare-versions $curver lt $myvulnver
				cmpres=$?
				case $cmpres in
						0) 
						res='lower'
						vuln=1
						;;
						1) 
						res='greater'
						vuln=0
						;;
				esac
			fi
			echo "My version ($curver) is $res than version ($myvulnver) vulnerable"
			if [ "$vuln" == "0" ]; then
				echo "System not vulnerable"
			else
				echo "System vulnerable!"

				if [ "$fix" == "1" ]; then
					echo "No fix available at this time"					
				fi
			fi
        else
			echo "?"
			exit 1
		fi
else	
	echo "Fix and check not available for your distribution!"	
	exit 1
fi