CVE-2018-8797
📋 TL;DR
CVE-2018-8797 is a critical heap-based buffer overflow vulnerability in rdesktop RDP client that allows remote attackers to execute arbitrary code on vulnerable systems. Attackers can exploit this by sending specially crafted RDP packets to trigger memory corruption. All users running vulnerable rdesktop versions are affected when connecting to malicious or compromised RDP servers.
💻 Affected Systems
- rdesktop
📦 What is this software?
Leap by Opensuse
Rdesktop by Rdesktop
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with SYSTEM/root privileges leading to complete system compromise, lateral movement, and data exfiltration.
Likely Case
Remote code execution leading to malware installation, credential theft, and persistent backdoor access.
If Mitigated
Denial of service or application crash if exploit fails or memory protections are in place.
🎯 Exploit Status
CheckPoint Research published detailed exploitation techniques. Exploit requires user to initiate RDP connection to attacker-controlled server.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: rdesktop v1.8.4 and later
Vendor Advisory: https://github.com/rdesktop/rdesktop/commit/4dca546d04321a610c1835010b5dad85163b65e1
Restart Required: Yes
Instructions:
1. Update rdesktop to version 1.8.4 or later using your package manager. 2. For Debian/Ubuntu: sudo apt update && sudo apt upgrade rdesktop. 3. For RHEL/CentOS: sudo yum update rdesktop. 4. Restart any active rdesktop sessions.
🔧 Temporary Workarounds
Network Segmentation
linuxRestrict RDP connections to trusted servers only using firewall rules.
iptables -A OUTPUT -p tcp --dport 3389 -d TRUSTED_SERVER_IP -j ACCEPT
iptables -A OUTPUT -p tcp --dport 3389 -j DROP
Use Alternative RDP Client
linuxTemporarily switch to alternative RDP clients like FreeRDP or Remmina until patched.
sudo apt install freerdp2-x11
sudo apt install remmina
🧯 If You Can't Patch
- Disable rdesktop usage and mandate alternative RDP clients
- Implement strict network controls to only allow RDP connections to verified internal servers
🔍 How to Verify
Check if Vulnerable:
Check rdesktop version: rdesktop --version | grep -o '[0-9]\.[0-9]\.[0-9]'Check Version:
rdesktop --versionVerify Fix Applied:
Verify version is 1.8.4 or higher: rdesktop --version | grep -q '1\.8\.[4-9]\|1\.9\|2\.' && echo 'Patched'📡 Detection & Monitoring
Log Indicators:
- Multiple failed RDP connections from single source
- RDP session crashes with memory access violations
- Unusual process spawning after RDP connections
Network Indicators:
- RDP connections to unknown or suspicious IP addresses
- Abnormal RDP packet sizes or patterns
- RDP traffic to non-standard ports
SIEM Query:
source="rdesktop.log" AND ("segmentation fault" OR "buffer overflow" OR "memory corruption")🔗 References
- http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00040.html
- http://www.securityfocus.com/bid/106938
- https://github.com/rdesktop/rdesktop/commit/4dca546d04321a610c1835010b5dad85163b65e1
- https://lists.debian.org/debian-lts-announce/2019/02/msg00030.html
- https://research.checkpoint.com/reverse-rdp-attack-code-execution-on-rdp-clients/
- https://security.gentoo.org/glsa/201903-06
- https://www.debian.org/security/2019/dsa-4394
- http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00040.html
- http://www.securityfocus.com/bid/106938
- https://github.com/rdesktop/rdesktop/commit/4dca546d04321a610c1835010b5dad85163b65e1
- https://lists.debian.org/debian-lts-announce/2019/02/msg00030.html
- https://research.checkpoint.com/reverse-rdp-attack-code-execution-on-rdp-clients/
- https://security.gentoo.org/glsa/201903-06
- https://www.debian.org/security/2019/dsa-4394
