CVE-2023-41724: Ivanti Standalone Sentry RCE Vulnerability

CVE-2023-41724 Overview

A critical command injection vulnerability exists in Ivanti Standalone Sentry prior to version 9.19.0. This flaw allows an unauthenticated threat actor to execute arbitrary commands on the underlying operating system of the appliance. The attacker must be within the same physical or logical network as the target device to exploit this vulnerability.

Critical Impact

Unauthenticated attackers on the adjacent network can achieve full remote code execution on vulnerable Ivanti Standalone Sentry appliances, potentially leading to complete system compromise.

Affected Products

• Ivanti Standalone Sentry versions prior to 9.19.0

Discovery Timeline

• 2024-03-31 - CVE-2023-41724 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-41724

Vulnerability Analysis

This vulnerability falls under the category of Command Injection (CWE-77) and Code Injection (CWE-94). The flaw resides in Ivanti Standalone Sentry, a gateway component that manages and secures traffic between mobile devices and back-end enterprise systems.

The vulnerability allows attackers to inject and execute arbitrary operating system commands on the underlying system. Because the vulnerability requires no authentication, any attacker with adjacent network access can exploit it to gain unauthorized control over the appliance. Successful exploitation grants the attacker the ability to execute commands with the privileges of the Sentry application, potentially allowing them to read sensitive configuration data, modify system settings, pivot to other internal systems, or establish persistent backdoor access.

Root Cause

The root cause of this vulnerability is improper input validation and insufficient sanitization of user-supplied data before it is passed to system command execution functions. Specifically, the application fails to properly neutralize special elements that could be interpreted as OS command separators or control characters, allowing attackers to inject malicious commands alongside legitimate input.

Attack Vector

The attack vector for CVE-2023-41724 is classified as Adjacent Network, meaning the attacker must have network-level access to the same physical or logical network segment as the vulnerable Ivanti Standalone Sentry appliance. This could include:

• Attackers on the same local area network (LAN)
• Attackers connected via VPN to the same network segment
• Attackers who have compromised another device on the network
• Insiders with physical or logical network access

Once network adjacency is established, the attacker can send specially crafted requests to the Sentry appliance that include malicious command sequences. These injected commands are then executed by the underlying operating system without proper validation or sanitization.

The command injection vulnerability allows attackers to craft malicious input that breaks out of the intended command context and executes arbitrary system commands. Typical exploitation involves using shell metacharacters such as semicolons, pipes, or command substitution syntax to append malicious commands to legitimate operations. For detailed technical information, refer to the Ivanti Security Advisory.

Detection Methods for CVE-2023-41724

Indicators of Compromise

• Unexpected outbound network connections from the Ivanti Sentry appliance to external IP addresses
• Unusual processes spawned by the Sentry application or its associated services
• Unauthorized modifications to system files, configurations, or user accounts on the appliance
• Suspicious log entries indicating command execution attempts with shell metacharacters

Detection Strategies

• Monitor Ivanti Sentry appliance logs for anomalous requests containing command injection patterns such as semicolons, pipes, backticks, or $(command) syntax
• Deploy network-based intrusion detection systems (IDS) to identify exploit attempts targeting Ivanti Sentry
• Implement behavioral analysis to detect unusual process execution chains on the appliance
• Review authentication and access logs for unauthorized access attempts from adjacent network segments

Monitoring Recommendations

• Enable comprehensive logging on all Ivanti Sentry appliances and forward logs to a centralized SIEM solution
• Configure alerting for any command execution attempts that include shell metacharacters or suspicious patterns
• Regularly audit network traffic to and from Sentry appliances for anomalous communication patterns
• Monitor for file integrity changes on the appliance using host-based monitoring solutions

How to Mitigate CVE-2023-41724

Immediate Actions Required

• Upgrade all Ivanti Standalone Sentry appliances to version 9.19.0 or later immediately
• Implement network segmentation to restrict access to Sentry appliances from untrusted network segments
• Conduct a security assessment to determine if any Sentry appliances may have been compromised
• Review and restrict which network segments have adjacent access to Sentry appliances

Patch Information

Ivanti has released a security patch addressing this vulnerability in Ivanti Standalone Sentry version 9.19.0. Organizations running vulnerable versions should apply this update as soon as possible. Detailed patch information and upgrade instructions are available in the Ivanti Security Advisory for CVE-2023-41724.

Workarounds

• Implement strict network access controls to limit which hosts can communicate with Sentry appliances
• Deploy a web application firewall (WAF) or network firewall rules to filter malicious input patterns
• Isolate Sentry appliances in a dedicated VLAN with restricted access from other network segments
• Monitor all traffic to Sentry appliances using intrusion prevention systems until patches can be applied

# Example: Network segmentation using iptables to restrict access to Sentry appliance
# Allow only trusted management network (10.10.10.0/24) to access Sentry on port 443
iptables -A INPUT -s 10.10.10.0/24 -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP