CVE-2017-8413 in DCS-1100
Summary
by MITRE
An issue was discovered on D-Link DCS-1100 and DCS-1130 devices. The device runs a custom daemon on UDP port 5978 which is called "dldps2121" and listens for broadcast packets sent on 255.255.255.255. This daemon handles custom D-Link UDP based protocol that allows D-Link mobile applications and desktop applications to discover D-Link devices on the local network. The binary processes the received UDP packets sent from any device in "main" function. One path in the function traverses towards a block of code that handles commands to be executed on the device. The custom protocol created by D-Link follows the following pattern: Packetlen, Type of packet; M=MAC address of device or broadcast; D=Device Type;C=base64 encoded command string;test=1111. If a packet is received with the packet type being "S" or 0x53 then the string passed in the "C" parameter is base64 decoded and then executed by passing into a System API. We can see at address 0x00009B44 that the string received in packet type subtracts 0x31 or "1" from the packet type and is compared against 0x22 or "double quotes". If that is the case, then the packet is sent towards the block of code that executes a command. Then the value stored in "C" parameter is extracted at address 0x0000A1B0. Finally, the string received is base 64 decoded and passed on to the system API at address 0x0000A2A8 as shown below. The same form of communication can be initiated by any process including an attacker process on the mobile phone or the desktop and this allows a third-party application on the device to execute commands on the device without any authentication by sending just 1 UDP packet with custom base64 encoding.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 10/15/2023
The vulnerability described in CVE-2017-8413 affects D-Link DCS-1100 and DCS-1130 network cameras, representing a critical security flaw in the device's discovery protocol implementation. These devices operate a custom daemon named "dldps2121" on UDP port 5978, which listens for broadcast packets sent to 255.255.255.255. This daemon facilitates device discovery for D-Link mobile and desktop applications through a proprietary UDP-based protocol that enables local network device enumeration. The vulnerability stems from insufficient input validation within the daemon's packet processing mechanism, specifically in the main function where received UDP packets are handled without proper authentication or authorization checks.
The technical flaw manifests in the protocol's handling of specific packet types, particularly when the packet type is "S" or 0x53. The daemon processes these packets by extracting the base64 encoded command string from the "C" parameter and executing it through a system API call. This execution path bypasses normal authentication mechanisms entirely, as the device processes commands directly from any source that can send a UDP packet to the designated port. The vulnerability's exploitation is facilitated by the protocol's design where packet type validation occurs through a simple arithmetic operation that subtracts 0x31 from the packet type and compares it against 0x22, creating a predictable execution flow that attackers can manipulate. The base64 decoding and system API call execution occur at specific memory addresses (0x0000A1B0 and 0x0000A2A8) where the unvalidated command string is directly passed to the system execution layer.
The operational impact of this vulnerability is severe, as it allows arbitrary command execution on affected devices with minimal attack complexity. An attacker requires only a single UDP packet with properly formatted parameters to gain full control over the device, making this vulnerability particularly dangerous for network security. The lack of authentication requirements means that any device on the local network, including unauthorized third-party applications running on mobile phones or desktop computers, can exploit this vulnerability. This creates a significant risk for surveillance systems, as attackers can execute malicious commands such as changing device configurations, accessing video feeds, or even installing malware on the affected cameras. The vulnerability effectively transforms these network cameras into potential attack vectors that can be leveraged for broader network infiltration or as part of larger attack campaigns targeting network infrastructure.
Mitigation strategies for CVE-2017-8413 should focus on both immediate network-level protections and long-term device security improvements. Network administrators should implement firewall rules to block UDP traffic on port 5978 from external sources and consider restricting access to this port to trusted internal IP addresses only. The most effective immediate solution involves disabling the problematic discovery service entirely or applying firmware updates from D-Link that address the authentication bypass vulnerability. Organizations should also consider network segmentation to isolate these devices from critical systems and implement intrusion detection systems to monitor for suspicious UDP traffic patterns on port 5978. This vulnerability aligns with CWE-78, which describes improper neutralization of special elements used in OS commands, and maps to ATT&CK technique T1059.007 for command and scripting interpreter, specifically through the use of system APIs for arbitrary command execution. The vulnerability also demonstrates characteristics of privilege escalation and remote code execution, making it a critical concern for organizations relying on network camera security for surveillance and access control systems.