CVE-2018-8800 – CVE-2018-8800 is a critical heap-based buffer o... (How to Fix)

Q: What is the severity of CVE-2018-8800?

CVE-2018-8800 has a CVSS score of 9.8 (CRITICAL). CVE-2018-8800 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 clipboard data during RDP sessions. All users running rdesktop versions up to v1.8.3 are affected.

📋 TL;DR

CVE-2018-8800 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 clipboard data during RDP sessions. All users running rdesktop versions up to v1.8.3 are affected.

💻 Affected Systems

Products:

rdesktop

Versions: All versions up to and including v1.8.3

Operating Systems: Linux, Unix-like systems, macOS

Default Config Vulnerable: ⚠️ Yes

Notes: Vulnerability triggers when processing clipboard data during RDP sessions. No special configuration required.

📦 What is this software?

⚠️ 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, but RCE remains probable.

🌐 Internet-Facing: HIGH - Attackers can exploit this remotely without authentication when rdesktop connects to malicious RDP servers.

🏢 Internal Only: HIGH - Internal attackers or compromised systems can exploit this during legitimate RDP sessions.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: CONFIRMED

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Check Point Research published detailed exploitation techniques. Exploit requires attacker to control RDP server or intercept/manipulate RDP traffic.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: v1.8.4 and later

Vendor Advisory: https://github.com/rdesktop/rdesktop/commit/4dca546d04321a610c1835010b5dad85163b65e1

Restart Required: No

Instructions:

1. Download rdesktop v1.8.4 or later from official repository. 2. Uninstall current version. 3. Install patched version. 4. Verify installation with 'rdesktop --version'.

🔧 Temporary Workarounds

Disable clipboard sharing

all

Prevent clipboard data exchange during RDP sessions to block exploitation vector

rdesktop -0 -r clipboard:off <server>

Use alternative RDP client

linux

Replace rdesktop with FreeRDP or other patched RDP clients

sudo apt-get install freerdp2-x11
xfreerdp /v:<server>

🧯 If You Can't Patch

Block outbound RDP connections to untrusted servers at network perimeter
Implement application whitelisting to prevent execution of unauthorized binaries

🔍 How to Verify

Check if Vulnerable:

Run 'rdesktop --version' and check if version is 1.8.3 or earlier

Check Version:

rdesktop --version | head -1

Verify Fix Applied:

Run 'rdesktop --version' and confirm version is 1.8.4 or later

📡 Detection & Monitoring

Log Indicators:

Multiple rdesktop crashes
Unusual clipboard operations in RDP logs
Suspicious process execution following RDP sessions

Network Indicators:

RDP connections to unknown/untrusted servers
Unusual clipboard data size in RDP traffic

SIEM Query:

process_name:"rdesktop" AND (event_type:crash OR parent_process:unusual)

📊 Metadata

CVE ID: CVE-2018-8800

CVSS v3 Score: 9.8 (CRITICAL)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-122

Published: February 5, 2019

Last Updated: November 21, 2024

🔗 References

http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00040.html Mailing List,Third Party Advisory
http://www.securityfocus.com/bid/106938 Third Party Advisory,VDB Entry
https://github.com/rdesktop/rdesktop/commit/4dca546d04321a610c1835010b5dad85163b65e1 Patch,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/02/msg00030.html Mailing List,Third Party Advisory
https://research.checkpoint.com/reverse-rdp-attack-code-execution-on-rdp-clients/ Third Party Advisory
https://security.gentoo.org/glsa/201903-06 Third Party Advisory
https://www.debian.org/security/2019/dsa-4394 Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00040.html Mailing List,Third Party Advisory
http://www.securityfocus.com/bid/106938 Third Party Advisory,VDB Entry
https://github.com/rdesktop/rdesktop/commit/4dca546d04321a610c1835010b5dad85163b65e1 Patch,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/02/msg00030.html Mailing List,Third Party Advisory
https://research.checkpoint.com/reverse-rdp-attack-code-execution-on-rdp-clients/ Third Party Advisory
https://security.gentoo.org/glsa/201903-06 Third Party Advisory
https://www.debian.org/security/2019/dsa-4394 Third Party Advisory

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🔗 Related Vulnerabilities

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