CVE-2012-6094
📋 TL;DR
CVE-2012-6094 is a critical vulnerability in CUPS (Common Unix Printing System) where the 'Listen localhost:631' configuration directive fails to restrict access to localhost only, allowing unauthorized remote access to the CUPS web interface. This affects systems running vulnerable versions of CUPS with the default or misconfigured network settings. Attackers can exploit this to gain unauthorized access to printing services and potentially execute further attacks.
💻 Affected Systems
- CUPS (Common Unix Printing System)
📦 What is this software?
Cups by Apple
⚠️ Risk & Real-World Impact
Worst Case
Remote attackers gain full administrative access to CUPS, potentially leading to remote code execution, system compromise, or lateral movement within the network.
Likely Case
Unauthorized users access the CUPS web interface to view print jobs, modify printer configurations, or disrupt printing services.
If Mitigated
If proper network segmentation and firewall rules are in place, impact is limited to denial of printing services within the local network segment.
🎯 Exploit Status
Exploitation requires network access to port 631. Public proof-of-concept scripts exist demonstrating unauthorized access to the CUPS web interface.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: CUPS 1.5.3 and later
Vendor Advisory: https://access.redhat.com/security/cve/cve-2012-6094
Restart Required: Yes
Instructions:
1. Update CUPS to version 1.5.3 or later using your distribution's package manager. 2. For Red Hat/CentOS: 'yum update cups'. 3. For Debian/Ubuntu: 'apt-get update && apt-get install cups'. 4. Restart CUPS service: 'systemctl restart cups' or 'service cups restart'.
🔧 Temporary Workarounds
Restrict Network Access with Firewall
linuxBlock external access to CUPS port 631 using firewall rules.
iptables -A INPUT -p tcp --dport 631 -j DROP
ufw deny 631/tcp
Configure CUPS to Listen Only on Localhost
linuxModify CUPS configuration to bind only to localhost interface.
echo 'Listen localhost:631' >> /etc/cups/cupsd.conf
systemctl restart cups
🧯 If You Can't Patch
- Implement strict network segmentation to isolate CUPS servers from untrusted networks.
- Deploy network-based intrusion detection systems (IDS) to monitor for unauthorized access attempts on port 631.
🔍 How to Verify
Check if Vulnerable:
Check CUPS version: 'cups-config --version' or 'rpm -q cups' or 'dpkg -l cups'. If version is below 1.5.3, check if port 631 is accessible from network: 'netstat -tlnp | grep 631' or 'ss -tlnp | grep 631'.Check Version:
cups-config --version || rpm -q cups || dpkg -l | grep cupsVerify Fix Applied:
Confirm CUPS version is 1.5.3 or later and verify port 631 is not listening on external interfaces: 'netstat -tlnp | grep 631' should show only 127.0.0.1:631 or ::1:631.📡 Detection & Monitoring
Log Indicators:
- Unauthorized access attempts in /var/log/cups/access_log or /var/log/cups/error_log
- Failed authentication attempts from non-localhost IP addresses
Network Indicators:
- Unexpected TCP connections to port 631 from external IPs
- HTTP requests to CUPS web interface from unauthorized sources
SIEM Query:
source="cups_access_log" AND (dest_port=631 AND NOT src_ip IN (127.0.0.1, ::1))🔗 References
- http://www.openwall.com/lists/oss-security/2013/01/04/5
- http://www.securityfocus.com/bid/57158
- https://access.redhat.com/security/cve/cve-2012-6094
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2012-6094
- https://bugzilla.suse.com/show_bug.cgi?id=CVE-2012-6094
- https://exchange.xforce.ibmcloud.com/vulnerabilities/82451
- https://security-tracker.debian.org/tracker/CVE-2012-6094
- http://www.openwall.com/lists/oss-security/2013/01/04/5
- http://www.securityfocus.com/bid/57158
- https://access.redhat.com/security/cve/cve-2012-6094
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2012-6094
- https://bugzilla.suse.com/show_bug.cgi?id=CVE-2012-6094
- https://exchange.xforce.ibmcloud.com/vulnerabilities/82451
- https://security-tracker.debian.org/tracker/CVE-2012-6094
