CVE-2021-42786
📋 TL;DR
CVE-2021-42786 allows remote attackers to execute arbitrary code on SteelCentral AppInternals Dynamic Sampling Agent (DSA) systems by sending malicious payloads to vulnerable API endpoints. This affects organizations using Riverbed SteelCentral AppInternals for application performance monitoring. The vulnerability stems from insufficient input validation in multiple API requests.
💻 Affected Systems
- Riverbed SteelCentral AppInternals Dynamic Sampling Agent (DSA)
📦 What is this software?
Steelcentral Appinternals Dynamic Sampling Agent by Riverbed
View all CVEs affecting Steelcentral Appinternals Dynamic Sampling Agent →
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to install malware, exfiltrate sensitive data, pivot to other systems, and establish persistent access.
Likely Case
Deployment of ransomware, cryptocurrency miners, or backdoors leading to operational disruption and data theft.
If Mitigated
Limited impact with proper network segmentation and access controls preventing exploitation attempts.
🎯 Exploit Status
Exploitation requires network access to the DSA agent's API endpoints (default port 7071).
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 12.14.0 and later
Vendor Advisory: https://aternity.force.com/customersuccess/s/article/Remote-Code-Execution-at-AgentControllerServlet-CVE-2021-42786
Restart Required: Yes
Instructions:
1. Download SteelCentral AppInternals version 12.14.0 or later from Riverbed support portal. 2. Stop the DSA agent service. 3. Install the updated version. 4. Restart the DSA agent service.
🔧 Temporary Workarounds
Network Access Restriction
allRestrict network access to DSA agent API endpoints (default TCP port 7071) using firewall rules.
# Linux iptables example: iptables -A INPUT -p tcp --dport 7071 -j DROP
# Windows Firewall: New-NetFirewallRule -DisplayName "Block DSA API" -Direction Inbound -LocalPort 7071 -Protocol TCP -Action Block
🧯 If You Can't Patch
- Implement strict network segmentation to isolate DSA agents from untrusted networks.
- Deploy web application firewall (WAF) rules to block malicious API requests targeting the vulnerable endpoints.
🔍 How to Verify
Check if Vulnerable:
Check DSA agent version via web interface at http://<agent_ip>:7071/ or review installed version in control panel.Check Version:
# Linux: cat /opt/riverbed/AppInternals/agent/version.txt
# Windows: Check installed programs in Control Panel or registry at HKLM\Software\Riverbed\AppInternals\Agent\VersionVerify Fix Applied:
Confirm version is 12.14.0 or later and test API endpoints with known payloads to ensure they are no longer vulnerable.📡 Detection & Monitoring
Log Indicators:
- Unusual process creation events from DSA agent
- Suspicious API requests to AgentControllerServlet endpoints in DSA logs
Network Indicators:
- Unusual outbound connections from DSA agent systems
- Traffic to DSA agent port 7071 from unexpected sources
SIEM Query:
source="*dsa*" AND ("AgentControllerServlet" OR "exec" OR "cmd")