CVE-2024-23049: B3log Symphony RCE Vulnerability

CVE-2024-23049 Overview

CVE-2024-23049 is a critical remote code execution vulnerability affecting B3log Symphony versions 3.6.3 and earlier. The vulnerability exists within the log4j component, allowing remote attackers to execute arbitrary code on vulnerable systems without requiring authentication or user interaction.

Critical Impact

Remote attackers can achieve full system compromise through arbitrary code execution via the vulnerable log4j component in B3log Symphony, potentially leading to complete loss of confidentiality, integrity, and availability.

Affected Products

• B3log Symphony version 3.6.3 and earlier
• Systems running vulnerable log4j components within Symphony deployments

Discovery Timeline

• 2024-02-05 - CVE-2024-23049 published to NVD
• 2025-06-17 - Last updated in NVD database

Technical Details for CVE-2024-23049

Vulnerability Analysis

This command injection vulnerability (CWE-77) allows remote attackers to execute arbitrary code through the log4j component integrated within B3log Symphony. The attack can be performed remotely over the network without requiring any privileges or user interaction, making it particularly dangerous for internet-facing deployments.

The vulnerability exploits weaknesses in how Symphony processes log messages through the log4j library. When specially crafted input is passed to logging functions, attackers can inject malicious commands that are then executed by the underlying system with the privileges of the Symphony application.

Root Cause

The root cause stems from improper neutralization of special elements used in a command (CWE-77). The log4j component within Symphony fails to properly sanitize user-controllable input before processing it, allowing attackers to inject and execute arbitrary commands. This is reminiscent of the broader Log4Shell vulnerability class, where JNDI lookup functionality can be abused to achieve remote code execution.

Attack Vector

The attack vector is network-based, meaning attackers can exploit this vulnerability remotely without requiring local access to the target system. The exploitation does not require authentication, privileges, or user interaction.

An attacker can craft malicious requests containing specially formatted strings that, when processed by the vulnerable log4j component, trigger command execution. This typically involves injecting JNDI lookup strings into user-controllable input fields that are subsequently logged by the application. For detailed technical information about the vulnerability, refer to the GitHub Issue Discussion.

Detection Methods for CVE-2024-23049

Indicators of Compromise

• Unusual outbound LDAP or RMI connections from Symphony application servers
• Suspicious JNDI lookup strings in application logs (e.g., ${jndi:ldap:// patterns)
• Unexpected child processes spawned by the Java process running Symphony
• Network connections to known malicious JNDI callback servers

Detection Strategies

• Monitor application logs for JNDI injection patterns such as ${jndi:, ${lower:, or nested variable expressions
• Deploy network-based intrusion detection rules to identify JNDI exploitation attempts in HTTP traffic
• Implement endpoint detection and response (EDR) monitoring for suspicious process chains originating from Java applications
• Review DNS query logs for unusual lookups that may indicate JNDI callback activity

Monitoring Recommendations

• Enable verbose logging on web application firewalls to capture and analyze incoming requests for malicious patterns
• Configure SIEM rules to alert on log4j exploitation indicators in real-time
• Monitor Java process behavior for signs of code execution such as unexpected network connections or file system modifications
• Establish baseline network behavior for Symphony deployments to detect anomalous outbound connections

How to Mitigate CVE-2024-23049

Immediate Actions Required

• Upgrade B3log Symphony to a version newer than 3.6.3 that addresses the vulnerable log4j component
• If immediate patching is not possible, implement network-level restrictions to block outbound LDAP and RMI connections from Symphony servers
• Apply web application firewall rules to block requests containing JNDI lookup patterns
• Review and audit all Symphony deployments for signs of prior exploitation

Patch Information

Organizations should upgrade to a patched version of B3log Symphony that addresses this vulnerability. Consult the GitHub Issue Discussion for the latest information on available fixes and remediation guidance from the vendor.

Workarounds

• Set the JVM option -Dlog4j2.formatMsgNoLookups=true to disable message lookup substitution
• Remove the JndiLookup class from the classpath using: zip -q -d log4j-core-*.jar org/apache/logging/log4j/core/lookup/JndiLookupClass
• Implement strict egress filtering to block outbound connections on ports commonly used for JNDI exploitation (LDAP port 389, RMI port 1099)
• Deploy a reverse proxy or WAF configured to sanitize or block requests containing log4j exploitation patterns

# Configuration example - Disable log4j lookups via JVM options
# Add to your Java startup configuration
JAVA_OPTS="$JAVA_OPTS -Dlog4j2.formatMsgNoLookups=true"

# Alternative: Remove JndiLookup class from log4j-core
# zip -q -d log4j-core-*.jar org/apache/logging/log4j/core/lookup/JndiLookup.class