CVE-2024-39950: Dahuasecurity NVR4104-4KS2/L DoS Flaw

CVE-2024-39950 Overview

CVE-2024-39950 affects multiple Dahua Network Video Recorder (NVR) and IP Camera (IPC) product lines. Attackers can send crafted data packets to a vulnerable network interface and trigger device initialization remotely. The flaw requires no authentication and no user interaction, exposing surveillance infrastructure to unauthorized reset and takeover. Affected models span the NVR4000-series (4KS2/L, 4KS2/I, 4KS3) and the IPC-HFS8849G-Z3-LED and IPC-HFS8449G-Z7-LED cameras. The vulnerability is classified under [CWE-121] Stack-based Buffer Overflow and [CWE-20] Improper Input Validation.

Critical Impact

Unauthenticated network attackers can force device initialization on Dahua NVRs and IP cameras, enabling credential reset and full administrative takeover of surveillance systems.

Affected Products

• Dahua NVR4000-series 4KS2/L firmware (NVR4104, NVR4108, NVR4116, NVR4204, NVR4208, NVR4216, NVR4232 variants)
• Dahua NVR4000-series 4KS2/I and 4KS3 firmware (NVR4416, NVR4432, NVR4816, NVR4832 variants)
• Dahua IPC-HFS8849G-Z3-LED and IPC-HFS8449G-Z7-LED IP cameras

Discovery Timeline

• 2024-07-31 - CVE-2024-39950 published to NVD
• 2025-09-30 - Last updated in NVD database

Technical Details for CVE-2024-39950

Vulnerability Analysis

The vulnerability resides in a network-facing interface exposed by Dahua NVR and IPC firmware. The interface accepts data packets that drive the device initialization workflow without enforcing proper authentication or input validation. An attacker on the network can craft packets that the device interprets as a legitimate initialization request. Successful exploitation impacts confidentiality, integrity, and availability of the surveillance device.

The presence of [CWE-121] Stack-based Buffer Overflow in the advisory indicates that the malformed packet handling also corrupts stack memory in the initialization routine. Combined with [CWE-20] Improper Input Validation, the flaw can lead beyond a logical reset to memory-level compromise of the embedded firmware.

Root Cause

The root cause is twofold. First, the initialization interface lacks state checks confirming whether the device has already completed initial setup, allowing repeated initialization to be triggered remotely. Second, the packet parser does not validate the size or structure of attacker-supplied fields before copying them onto the stack, producing a buffer overflow condition in the firmware.

Attack Vector

The attack vector is network-based and requires no privileges or user interaction. An attacker with reachability to the device management interface, including any NVR or camera exposed to the internet or to a flat internal network, can deliver crafted packets directly. Dahua NVRs are frequently exposed via TCP ports 37777, 80, and 443. Successful initialization grants the attacker the ability to set new administrative credentials, after which the device can be repurposed for surveillance interception, lateral movement, or botnet enrollment.

No verified public exploit code is currently available. See the Dahua Security Advisory #768 for vendor-supplied technical details.

Detection Methods for CVE-2024-39950

Indicators of Compromise

• Unexpected device reboot or return to factory initialization state on Dahua NVR or IPC endpoints
• Administrative password reset events on surveillance devices that were not initiated by an authorized operator
• Inbound connections to Dahua management ports (TCP 37777, 80, 443) from untrusted source addresses
• New or modified administrator accounts on NVR or camera web interfaces without a corresponding change ticket

Detection Strategies

• Monitor network traffic for malformed or oversized packets directed at Dahua device management ports and correlate with subsequent device reinitialization events
• Compare device configuration baselines against the running configuration to identify silent reset to defaults
• Enable syslog forwarding from Dahua devices to a central log platform and alert on device init, factory reset, or admin password change events

Monitoring Recommendations

• Inventory all Dahua NVR and IPC devices and confirm firmware versions against the vendor advisory
• Track authentication failures and configuration change events on surveillance subnets continuously
• Establish alerting for any external traffic reaching surveillance VLANs, which should normally be segmented

How to Mitigate CVE-2024-39950

Immediate Actions Required

• Apply Dahua firmware updates referenced in Dahua Security Advisory #768 to all affected NVR and IPC models
• Remove direct internet exposure of Dahua management interfaces and place devices behind a firewall or VPN
• Audit administrator accounts on all surveillance devices and rotate credentials after patching

Patch Information

Dahua has published remediated firmware for the affected NVR4000-series and IPC products. Refer to Dahua Security Advisory #768 for the specific firmware build numbers per model and the upgrade procedure. Verify the firmware hash after download and confirm device version through the web management interface after upgrade.

Workarounds

• Restrict access to Dahua management ports (TCP 37777, 80, 443) using firewall ACLs that permit only authorized administrative subnets
• Segment surveillance devices onto a dedicated VLAN with no direct route to or from the internet
• Disable UPnP and port forwarding for surveillance devices on perimeter routers until patched firmware is deployed

# Example firewall ACL restricting access to Dahua management interfaces
iptables -A INPUT -p tcp --dport 37777 -s 10.10.50.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 37777 -j DROP
iptables -A INPUT -p tcp --dport 80 -s 10.10.50.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 10.10.50.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP