CVE-2023-4450: Jeecg JimuReport RCE Vulnerability

CVE-2023-4450 Overview

CVE-2023-4450 is a critical Server-Side Template Injection (SSTI) vulnerability discovered in jeecgboot JimuReport versions up to 1.6.0. The vulnerability exists within the Template Handler component and allows remote attackers to perform injection attacks that can lead to Remote Code Execution (RCE). The exploit has been publicly disclosed, making this vulnerability particularly dangerous for organizations running vulnerable versions of JimuReport.

Critical Impact

This vulnerability allows unauthenticated remote attackers to execute arbitrary code on affected JimuReport servers through template injection, potentially leading to complete system compromise.

Affected Products

• JimuReport versions up to and including 1.6.0
• jeecgboot JimuReport (all installations prior to version 1.6.1)
• Applications integrating vulnerable JimuReport template handling components

Discovery Timeline

• 2023-08-21 - CVE-2023-4450 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-4450

Vulnerability Analysis

CVE-2023-4450 is a Server-Side Template Injection (SSTI) vulnerability affecting the Template Handler component in JimuReport. SSTI vulnerabilities occur when user-controlled input is embedded into template engines without proper sanitization, allowing attackers to inject malicious template directives that are executed server-side.

In this case, the Template Handler fails to properly sanitize user input before processing it through the template engine. When an attacker submits specially crafted template syntax, the server interprets and executes the malicious payload, leading to Remote Code Execution. This is particularly severe as it requires no authentication and can be exploited remotely over the network with low attack complexity.

The vulnerability has attracted significant attention from threat actors, as evidenced by its extremely high EPSS score of 90.23%, placing it in the 99.58th percentile for exploitation probability. This indicates that active exploitation attempts are highly likely in the wild.

Root Cause

The root cause of this vulnerability lies in improper input validation and sanitization within the Template Handler component. The application fails to adequately filter or escape user-supplied data before incorporating it into template processing logic. This allows template injection payloads to be interpreted as executable code rather than treated as literal data.

Specifically, the vulnerability stems from CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), commonly known as Injection. The template engine processes attacker-controlled input without proper contextual output encoding, enabling arbitrary template directive execution.

Attack Vector

The attack vector for CVE-2023-4450 is network-based, allowing remote exploitation without authentication. An attacker can craft malicious HTTP requests containing SSTI payloads directed at the vulnerable Template Handler endpoint. The exploitation flow typically involves:

1. Identifying a JimuReport instance running a vulnerable version (≤1.6.0)
2. Locating endpoints that process template input
3. Injecting template-specific syntax designed to achieve code execution
4. The template engine evaluates the malicious payload server-side
5. Arbitrary code execution occurs with the privileges of the JimuReport application

Technical details and proof-of-concept information have been documented in the GitHub PoC Report. Additional vulnerability intelligence is available through VulDB.

Detection Methods for CVE-2023-4450

Indicators of Compromise

• Unusual HTTP requests to JimuReport template processing endpoints containing suspicious template syntax patterns
• Web server logs showing requests with template injection payloads such as expression language syntax or special template directives
• Unexpected process spawning or command execution originating from the JimuReport application process
• Outbound network connections from JimuReport servers to unknown external IP addresses

Detection Strategies

• Deploy Web Application Firewall (WAF) rules to detect and block common SSTI payload patterns in HTTP requests
• Monitor application logs for anomalous template processing errors or exceptions that may indicate injection attempts
• Implement endpoint detection and response (EDR) solutions like SentinelOne to detect post-exploitation behaviors such as unauthorized process execution
• Conduct regular vulnerability scanning to identify JimuReport instances running versions prior to 1.6.1

Monitoring Recommendations

• Enable verbose logging for the JimuReport Template Handler component to capture detailed request information
• Set up alerting for any process execution initiated by the JimuReport application that falls outside normal operational patterns
• Monitor network traffic for data exfiltration attempts or reverse shell connections originating from JimuReport servers
• Implement file integrity monitoring on JimuReport installation directories to detect unauthorized modifications

How to Mitigate CVE-2023-4450

Immediate Actions Required

• Upgrade JimuReport to version 1.6.1 or later immediately, as this version addresses the vulnerability
• If immediate patching is not possible, restrict network access to JimuReport instances using firewall rules to limit exposure
• Review web server access logs for signs of exploitation attempts or successful compromise
• Isolate affected systems from critical network segments until patching is complete

Patch Information

The vendor has released version 1.6.1 of JimuReport which remediates this vulnerability. Organizations should update to this version or later as the primary mitigation strategy. The upgrade addresses the improper input handling in the Template Handler component that enabled the SSTI attack.

Verify your current JimuReport version and compare it against the fixed release. All instances running version 1.6.0 or earlier should be considered vulnerable and prioritized for immediate updates.

Workarounds

• Implement network-level access controls to restrict access to JimuReport administration and template processing interfaces to trusted IP addresses only
• Deploy a Web Application Firewall (WAF) with rules configured to block template injection patterns and suspicious payloads
• Disable or restrict access to the vulnerable Template Handler functionality if it is not required for business operations
• Consider running JimuReport in an isolated container or sandbox environment with minimal privileges to limit the impact of potential exploitation

# Example: Restrict access to JimuReport using iptables
# Allow only trusted IP ranges to access the JimuReport service port
iptables -A INPUT -p tcp --dport 8080 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP