📄 Description (English)
Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to sanitize user-controlled post content in the mmctl commands terminal output which allows attackers to manipulate administrator terminals via crafted messages containing ANSI and OSC escape sequences that enable screen manipulation, fake prompts, and clipboard hijacking.. Mattermost Advisory ID: MMSA-2026-00599
🤖 AI Executive Summary
Mattermost versions 11.2.x through 11.2.2, 10.11.x through 10.11.10, 11.3.x through 11.3.1, and 11.4.0 contain an ANSI/OSC escape sequence injection vulnerability in mmctl command terminal output. Attackers can craft malicious messages to manipulate administrator terminals, create fake prompts, and hijack clipboard contents. With a CVSS score of 8.0 and no patch currently available, this poses significant risk to organizations using Mattermost for internal communications, particularly those with administrative access to sensitive systems.
📄 Description (Arabic)
🤖 AI Intelligence Analysis Analyzed: Apr 26, 2026 21:37
🇸🇦 Saudi Arabia Impact Assessment
Saudi organizations using Mattermost for internal communications face significant risk, particularly: (1) Government agencies and NCA-regulated entities relying on Mattermost for secure communications — administrators could be compromised via terminal manipulation; (2) Banking sector (SAMA-regulated) — if Mattermost integrates with administrative workflows, attackers could manipulate financial system access; (3) Energy sector (ARAMCO, Saudi Electricity Company) — critical infrastructure administrators using mmctl commands are vulnerable to credential theft and system access manipulation; (4) Telecommunications (STC, Mobily) — network administrators could be targeted; (5) Healthcare institutions — patient data access could be compromised through administrator terminal hijacking. The vulnerability is particularly dangerous in Saudi organizations with centralized administrative access patterns.
🏢 Affected Saudi Sectors
Government & Public Administration
Banking & Financial Services
Energy & Utilities
Telecommunications
Healthcare
Defense & Security
Critical Infrastructure
🎯 MITRE ATT&CK Techniques
T1059.004 - Command and Scripting Interpreter: Unix Shell (mmctl terminal manipulation)
T1036.001 - Masquerading: Invalid Code Signature (fake prompts via escape sequences)
T1056.004 - Input Capture: Clipboard Data (clipboard hijacking via OSC sequences)
T1021.004 - Remote Services: SSH/Telnet (terminal session manipulation)
T1550.001 - Use Alternate Authentication Material: Application Access Token (admin credential theft)
T1040 - Network Sniffing (potential data exfiltration via clipboard)
T1070.001 - Indicator Removal: Clear Logs (potential log manipulation)
⚖️ Saudi Risk Score (AI)
8.2
/ 10.0
🔧 Remediation Steps (English)
IMMEDIATE ACTIONS:
1. Audit all Mattermost instances for affected versions (10.11.x ≤10.11.10, 11.2.x ≤11.2.2, 11.3.x ≤11.3.1, 11.4.0)
2. Restrict mmctl command access to trusted networks only via firewall rules
3. Disable direct terminal access to mmctl for non-essential administrators
4. Review Mattermost audit logs for suspicious message content containing ANSI escape sequences (look for patterns: ESC[, ESC], OSC sequences)
COMPENSATING CONTROLS (until patch available):
5. Implement terminal emulator hardening: disable ANSI/OSC sequence processing in terminal applications used by administrators
6. Use terminal multiplexers (tmux/screen) with escape sequence filtering enabled
7. Implement input validation at network level to strip ANSI/OSC sequences from Mattermost messages before display
8. Enforce multi-factor authentication for all administrative accounts accessing mmctl
9. Monitor for clipboard access anomalies and unauthorized system command execution
DETECTION RULES:
10. Alert on messages containing: ESC[, ESC], OSC (\x1b\], \x07), or hex sequences 1b5b, 1b5d
11. Monitor mmctl process execution for unusual child processes or clipboard operations
12. Log all administrative terminal sessions and review for screen manipulation indicators
13. Watch for failed authentication attempts following Mattermost message activity
PATCHING:
14. Subscribe to Mattermost security advisories for patch availability
15. Plan immediate upgrade to patched versions once released
16. Test patches in isolated environment before production deployment
🔧 خطوات المعالجة (العربية)
الإجراءات الفورية:
1. تدقيق جميع نسخ Mattermost للإصدارات المتأثرة (10.11.x ≤10.11.10، 11.2.x ≤11.2.2، 11.3.x ≤11.3.1، 11.4.0)
2. تقييد وصول أوامر mmctl إلى الشبكات الموثوقة فقط عبر قواعد جدار الحماية
3. تعطيل الوصول المباشر للطرفية إلى mmctl للمسؤولين غير الأساسيين
4. مراجعة سجلات تدقيق Mattermost للمحتوى المريب الذي يحتوي على تسلسلات ANSI (ابحث عن: ESC[، ESC]، تسلسلات OSC)
الضوابط البديلة (حتى توفر التصحيح):
5. تطبيق تقسية محاكي الطرفية: تعطيل معالجة تسلسلات ANSI/OSC في تطبيقات الطرفية المستخدمة من قبل المسؤولين
6. استخدام مضاعفات الطرفية (tmux/screen) مع تفعيل تصفية تسلسلات الهروب
7. تطبيق التحقق من الإدخال على مستوى الشبكة لإزالة تسلسلات ANSI/OSC من رسائل Mattermost قبل العرض
8. فرض المصادقة متعددة العوامل لجميع حسابات المسؤولين التي تصل إلى mmctl
9. مراقبة شذوذ الوصول إلى الحافظة والتنفيذ غير المصرح به لأوامر النظام
قواعد الكشف:
10. تنبيه على الرسائل التي تحتوي على: ESC[، ESC]، OSC (\x1b\]، \x07)، أو تسلسلات سادسة عشرية 1b5b، 1b5d
11. مراقبة تنفيذ عملية mmctl للعمليات الفرعية غير العادية أو عمليات الحافظة
12. تسجيل جميع جلسات الطرفية الإدارية ومراجعتها للبحث عن مؤشرات التلاعب بالشاشة
13. مراقبة محاولات المصادقة الفاشلة التي تتبع نشاط رسالة Mattermost
التصحيح:
14. الاشتراك في تنبيهات أمان Mattermost لتوفر التصحيح
15. التخطيط للترقية الفورية إلى الإصدارات المصححة بمجرد إصدارها
16. اختبار التصحيحات في بيئة معزولة قبل نشرها في الإنتاج
📋 Regulatory Compliance Mapping
🟢 NCA ECC 2024
ECC 2024 A.5.1.1 - Access Control Policies (administrative access restrictions)
ECC 2024 A.6.1.1 - User Registration and Access Rights Management
ECC 2024 A.8.2.1 - User Access Management (terminal access controls)
ECC 2024 A.12.4.1 - Event Logging (audit trail of mmctl commands)
ECC 2024 A.13.1.1 - Information Security Incident Management (detection and response)
🔵 SAMA CSF
SAMA CSF ID.AM-2 - Software, platforms, and applications are cataloged (Mattermost version inventory)
SAMA CSF PR.AC-1 - Identities and credentials are issued, managed, verified, revoked, and audited (admin access control)
SAMA CSF PR.AC-4 - Access is managed based on the principle of least privilege (mmctl access restriction)
SAMA CSF DE.CM-1 - The network is monitored to detect potential cybersecurity events (ANSI sequence detection)
SAMA CSF RS.AN-1 - Notifications from detection systems are investigated (incident response)
🟡 ISO 27001:2022
ISO 27001:2022 A.5.3 - Segregation of duties (administrative access separation)
ISO 27001:2022 A.6.2 - User access provisioning (access control policies)
ISO 27001:2022 A.8.1 - User endpoint devices (terminal hardening)
ISO 27001:2022 A.8.2 - Privileged access rights (mmctl command restrictions)
ISO 27001:2022 A.8.3 - Information access restriction (least privilege)
ISO 27001:2022 A.12.4 - Logging (audit trail requirements)
🟣 PCI DSS v4.0.1
PCI DSS 2.1 - Restrict access to system components by business need to know
PCI DSS 7.1 - Limit access to system components by business need to know
PCI DSS 8.1 - Assign unique ID to each person with computer access
PCI DSS 10.2 - Implement automated audit trails for all access to cardholder data
🔗 References & Sources 1
📦 Affected Products / CPE 4 entries
mattermost:mattermost_server
mattermost:mattermost_server
mattermost:mattermost_server
mattermost:mattermost_server:11.4.0