CVE-2024-39349: Synology BC500 Firmware RCE Vulnerability

CVE-2024-39349 Overview

A critical buffer overflow vulnerability has been identified in the libjansson component of Synology Camera Firmware affecting the BC500 and TC500 camera models. This classic buffer overflow (CWE-120) occurs when data is copied without properly validating the input size, allowing remote attackers to execute arbitrary code on vulnerable devices. Notably, this vulnerability is specific to Synology's implementation and does not affect the upstream jansson library.

Critical Impact

Remote attackers can achieve arbitrary code execution on vulnerable Synology cameras via network-based attack vectors, potentially leading to complete device compromise, surveillance footage access, and lateral movement within networks.

Affected Products

• Synology BC500 with firmware versions before 1.0.7-0298
• Synology TC500 with firmware versions before 1.0.7-0298
• Synology BC500 Firmware
• Synology TC500 Firmware

Discovery Timeline

• 2024-06-28 - CVE-2024-39349 published to NVD
• 2025-04-10 - Last updated in NVD database

Technical Details for CVE-2024-39349

Vulnerability Analysis

This vulnerability represents a classic buffer overflow condition (CWE-120) within the libjansson component used by Synology's camera firmware. The flaw enables remote code execution through improper handling of input data, where buffer copy operations fail to validate the size of incoming data against the allocated buffer capacity.

The network-accessible nature of this vulnerability is particularly concerning for IoT security cameras, as these devices are often deployed in sensitive environments and may be exposed to untrusted networks. The vulnerability requires no authentication or user interaction to exploit, making it an attractive target for attackers seeking to compromise surveillance infrastructure.

Root Cause

The root cause lies in the improper implementation of the libjansson library within Synology's camera firmware. During data processing operations, the code performs buffer copy operations without adequately checking the size of the input data against the destination buffer's capacity. This oversight allows an attacker to supply crafted input that exceeds buffer boundaries, corrupting adjacent memory regions.

It is important to note that this vulnerability is specific to Synology's modified or integrated version of libjansson and does not affect the upstream open-source jansson library used in other applications.

Attack Vector

The attack can be executed remotely over the network without requiring any authentication or user interaction. An attacker with network access to a vulnerable Synology camera can craft malicious requests containing oversized input data designed to trigger the buffer overflow condition.

The exploitation process involves sending specially crafted network packets to the vulnerable camera. When the libjansson component processes this malicious input, the buffer overflow occurs, allowing the attacker to overwrite critical memory structures. Successful exploitation leads to arbitrary code execution with the privileges of the camera firmware process, potentially granting full control over the device.

Detection Methods for CVE-2024-39349

Indicators of Compromise

• Unusual network traffic patterns or connections from Synology BC500 or TC500 cameras to unknown external IP addresses
• Unexpected firmware behavior, crashes, or restarts of camera services
• Anomalous log entries indicating processing errors in the libjansson component
• Unauthorized configuration changes or new user accounts on camera devices

Detection Strategies

• Monitor network traffic to and from Synology cameras for anomalous patterns, especially oversized or malformed JSON data
• Implement intrusion detection system (IDS) rules to identify potential buffer overflow exploitation attempts targeting camera firmware
• Perform regular firmware version audits to identify devices running vulnerable versions (before 1.0.7-0298)
• Enable and review camera device logs for signs of exploitation or abnormal service behavior

Monitoring Recommendations

• Deploy network segmentation to isolate IoT cameras from critical network segments
• Implement continuous vulnerability scanning to identify unpatched Synology cameras
• Configure SIEM alerts for unusual camera device behavior or network anomalies
• Establish baseline behavior profiles for camera devices to detect deviations

How to Mitigate CVE-2024-39349

Immediate Actions Required

• Update all Synology BC500 and TC500 cameras to firmware version 1.0.7-0298 or later immediately
• Isolate vulnerable cameras from untrusted networks until patches can be applied
• Review network access controls to limit exposure of camera management interfaces
• Audit camera access logs for any signs of prior exploitation

Patch Information

Synology has released firmware version 1.0.7-0298 to address this vulnerability. Administrators should immediately update affected BC500 and TC500 camera devices through the Synology Camera management interface or by downloading the firmware from Synology's support portal. For detailed patch information and download links, refer to the Synology Security Advisory SA-23-15.

Workarounds

• Restrict network access to affected cameras using firewall rules to allow connections only from trusted management hosts
• Place vulnerable cameras behind a VPN or on an isolated VLAN with no direct internet exposure
• Disable any unnecessary network services on the camera devices to reduce attack surface
• Monitor camera firmware behavior closely while awaiting patch deployment

# Network isolation example using iptables
# Restrict camera access to management subnet only
iptables -A INPUT -s 192.168.10.0/24 -d <camera_ip> -j ACCEPT
iptables -A INPUT -d <camera_ip> -j DROP