CVE-2011-1930
📋 TL;DR
CVE-2011-1930 is a command injection vulnerability in klibc's DHCP client (ipconfig) where specially crafted DHCP responses can execute arbitrary code. This affects systems using klibc 1.5.20-1.5.21 for network initialization, potentially allowing remote attackers to gain root privileges on vulnerable systems during boot.
💻 Affected Systems
- klibc
📦 What is this software?
Klibc by Klibc Project
⚠️ Risk & Real-World Impact
Worst Case
Remote unauthenticated attacker gains root privileges on vulnerable system during network initialization, leading to complete system compromise.
Likely Case
Attacker on local network sends malicious DHCP response during system boot, executing arbitrary code with root privileges.
If Mitigated
Systems not using klibc DHCP client or with updated versions are unaffected; isolated networks reduce exposure.
🎯 Exploit Status
Exploitation requires control of DHCP server or ability to spoof DHCP responses. Public exploit details exist in security advisories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: klibc 1.5.22 and later
Vendor Advisory: https://security-tracker.debian.org/tracker/CVE-2011-1930
Restart Required: Yes
Instructions:
1. Update klibc package to version 1.5.22 or later. 2. Update initramfs: 'update-initramfs -u' (Debian/Ubuntu) or 'dracut --force' (RHEL). 3. Reboot system.
🔧 Temporary Workarounds
Disable klibc DHCP client
linuxConfigure system to use alternative DHCP client or static IP during boot
Edit initramfs configuration to remove ipconfig or set static IP
Network segmentation
allIsolate DHCP servers and restrict DHCP traffic to trusted sources
🧯 If You Can't Patch
- Implement strict network controls: allow DHCP only from trusted servers using firewall rules
- Monitor DHCP traffic for anomalies and consider using static IP addresses for critical systems
🔍 How to Verify
Check if Vulnerable:
Check klibc version: 'dpkg -l | grep klibc' (Debian) or 'rpm -qa | grep klibc' (RHEL). If version is 1.5.20 or 1.5.21, system is vulnerable.Check Version:
dpkg -l | grep klibc # Debian/Ubuntu
rpm -qa | grep klibc # RHEL/CentOSVerify Fix Applied:
Verify klibc version is 1.5.22 or later and check that initramfs has been regenerated.📡 Detection & Monitoring
Log Indicators:
- Unusual DHCP responses in system logs during boot
- Failed network initialization attempts
Network Indicators:
- Malformed DHCP packets with shell metacharacters
- DHCP responses from untrusted sources
SIEM Query:
source="dhcp" AND (command="*" OR shell="*" OR metacharacter="*" OR unusual_option="*")🔗 References
- http://security.gentoo.org/glsa/glsa-201309-21.xml
- http://www.openwall.com/lists/oss-security/2012/05/22/12
- http://www.securityfocus.com/bid/47924
- https://access.redhat.com/security/cve/cve-2011-1930
- https://security-tracker.debian.org/tracker/CVE-2011-1930
- http://security.gentoo.org/glsa/glsa-201309-21.xml
- http://www.openwall.com/lists/oss-security/2012/05/22/12
- http://www.securityfocus.com/bid/47924
- https://access.redhat.com/security/cve/cve-2011-1930
- https://security-tracker.debian.org/tracker/CVE-2011-1930
