CVE-2017-8416 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 processing of packets which does an unbounded copy operation which allows to overflow the buffer. The custom protocol created by Dlink 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 We can see at address function starting at address 0x0000DBF8 handles the entire UDP packet and performs an insecure copy using strcpy function at address 0x0000DC88. This results in overflowing the stack pointer after 1060 characters and thus allows to control the PC register and results in code execution. 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.
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Analysis
by VulDB Data Team • 10/15/2023
The vulnerability identified in CVE-2017-8416 affects D-Link DCS-1100 and DCS-1130 network cameras through a critical buffer overflow in the dldps2121 daemon running on UDP port 5978. This daemon implements a custom D-Link protocol designed for device discovery within local networks, enabling mobile and desktop applications to locate D-Link devices. The protocol structure follows a specific format including packet length, packet type, MAC address, device type, and base64 encoded command strings, with a test parameter set to 1111. The vulnerability stems from an insecure implementation in the main processing function where the daemon receives and handles UDP packets from any source on the broadcast address 255.255.255.255. The technical flaw manifests at address 0x0000DC88 where the strcpy function performs an unbounded copy operation without proper bounds checking, leading to a stack-based buffer overflow. This specific implementation violates CWE-121, which addresses stack-based buffer overflow conditions, and more specifically CWE-125, which covers out-of-bounds read vulnerabilities. The attack vector requires only a single UDP packet sent from any device on the network, making it particularly dangerous as it can be exploited by third-party applications without authentication. The buffer overflow occurs after 1060 characters, allowing attackers to overwrite the stack pointer and subsequently control the program counter register, enabling arbitrary code execution. This vulnerability aligns with ATT&CK technique T1059.007, which describes the execution of code through command and scripting interpreter, specifically targeting network services and daemons. The implications extend beyond simple privilege escalation as the attacker gains complete control over the device's operating system, potentially allowing for persistent access, data exfiltration, or use as a pivot point for further network attacks. The vulnerability represents a classic case of unsafe string handling in embedded systems where the lack of input validation and bounds checking creates a path for remote code execution. The fact that this daemon listens on a broadcast address and accepts packets from any source makes it particularly susceptible to exploitation and demonstrates poor network security design principles. Organizations should consider implementing network segmentation and firewall rules to restrict access to UDP port 5978, while also ensuring that affected devices receive appropriate firmware updates from D-Link to address this critical vulnerability. The attack scenario allows for immediate code execution without requiring any authentication, making it a severe threat to network security and device integrity. This vulnerability highlights the importance of secure coding practices in embedded systems and the dangers of implementing custom protocols without proper security considerations, particularly when dealing with network-facing services that handle untrusted input. The exploitation of this vulnerability could lead to complete device compromise and unauthorized access to network cameras, potentially exposing sensitive surveillance data and creating entry points for broader network infiltration attempts.