📄 Description (English)
UltraVNC Viewer 1.2.2.4 contains a denial of service vulnerability that allows attackers to crash the application by supplying an oversized string to the VNC Server input field. Attackers can paste a malicious string containing 256 repeated characters into the VNC Server field and click Connect to trigger a buffer overflow that crashes the viewer.
🤖 AI Executive Summary
CVE-2019-25600 is a buffer overflow vulnerability in UltraVNC Viewer 1.2.2.4 that allows remote denial of service through oversized input strings. An attacker can crash the application by supplying 256+ repeated characters in the VNC Server field, disrupting remote access capabilities. While no public exploit exists and patching is unavailable, the vulnerability poses operational risk to organizations relying on UltraVNC for remote administration.
📄 Description (Arabic)
🤖 AI Intelligence Analysis Analyzed: May 10, 2026 22:01
🇸🇦 Saudi Arabia Impact Assessment
Saudi government agencies, financial institutions, and critical infrastructure operators using UltraVNC for remote administration face operational disruption risk. ARAMCO and energy sector facilities, banking institutions under SAMA oversight, and NCA-regulated government networks are particularly vulnerable if UltraVNC is deployed for system administration. Telecom operators (STC, Mobily) and healthcare facilities may experience service interruptions if remote support relies on affected VNC versions.
🏢 Affected Saudi Sectors
Government Administration
Banking and Financial Services
Energy and Utilities
Healthcare
Telecommunications
Critical Infrastructure
🎯 MITRE ATT&CK Techniques
⚖️ Saudi Risk Score (AI)
5.2
/ 10.0
🔧 Remediation Steps (English)
Immediate Actions:
1. Audit all systems running UltraVNC Viewer 1.2.2.4 and document inventory
2. Restrict VNC Server field input validation at application level
3. Implement network segmentation to limit VNC access to trusted administrative networks only
4. Disable UltraVNC Viewer if alternative remote access solutions are available
Compensating Controls:
1. Deploy input validation filters blocking strings exceeding 255 characters in VNC connection dialogs
2. Implement application whitelisting to prevent unauthorized VNC usage
3. Monitor VNC connection attempts and log all connection failures
4. Use VNC over SSH tunnels with strict access controls
5. Upgrade to UltraVNC 1.2.2.5 or later when available
Detection Rules:
1. Monitor for repeated application crashes of UltraVNC Viewer processes
2. Alert on VNC connection attempts with oversized hostname/server field inputs
3. Track failed VNC connection events in application logs
🔧 خطوات المعالجة (العربية)
الإجراءات الفورية:
1. تدقيق جميع الأنظمة التي تعمل بـ UltraVNC Viewer 1.2.2.4 وتوثيق المخزون
2. تقييد التحقق من صحة إدخال حقل خادم VNC على مستوى التطبيق
3. تنفيذ تقسيم الشبكة لتحديد وصول VNC للشبكات الإدارية الموثوقة فقط
4. تعطيل UltraVNC Viewer إذا كانت حلول الوصول عن بعد البديلة متاحة
الضوابط التعويضية:
1. نشر مرشحات التحقق من صحة الإدخال لحظر السلاسل التي تتجاوز 255 حرفاً في حوارات اتصال VNC
2. تنفيذ القائمة البيضاء للتطبيقات لمنع استخدام VNC غير المصرح به
3. مراقبة محاولات اتصال VNC وتسجيل جميع فشل الاتصال
4. استخدام VNC عبر نفق SSH مع ضوابط وصول صارمة
5. الترقية إلى UltraVNC 1.2.2.5 أو إصدار أحدث عند توفره
قواعد الكشف:
1. مراقبة أعطال تطبيق UltraVNC Viewer المتكررة
2. التنبيه على محاولات اتصال VNC بحقول خادم مفرطة الحجم
3. تتبع أحداث فشل اتصال VNC في سجلات التطبيق
📋 Regulatory Compliance Mapping
🟢 NCA ECC 2024
ECC 2024 A.14.2.1 - System change control and testing
ECC 2024 A.12.6.1 - Management of technical vulnerabilities
ECC 2024 A.12.3.1 - Segregation of networks
🔵 SAMA CSF
ID.BE-5 - Organizational resilience
PR.DS-6 - Integrity checking mechanisms
DE.CM-1 - The network is monitored to detect potential cybersecurity events
🟡 ISO 27001:2022
A.12.2.1 - Restrictions on software installation
A.12.6.1 - Management of technical vulnerabilities
A.13.1.3 - Segregation of networks
🟣 PCI DSS v4.0.1
Requirement 6.2 - Security patches must be installed within defined timeframe
🔗 References & Sources 4
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https://www.exploit-db.com/exploits/46702
disclosure@vulncheck.com
https://www.uvnc.com/
disclosure@vulncheck.com
https://www.uvnc.com/downloads/ultravnc/126-download-ultravnc-1224.html
disclosure@vulncheck.com
https://www.vulncheck.com/advisories/ultravnc-viewer-denial-of-service-via-buffer-overflow
disclosure@vulncheck.com