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.
This is a vulnerability exploitable with adjacent network access and requires the attacker to have
access to either the broadcast or collision domain of the vulnerable software. Examples of
local networks include local IP subnet, Bluetooth, IEEE 802.11, and local Ethernet
Specialized access conditions or extenuating circumstances do not exist. The following are examples:
The affected product typically requires access to a wide range of systems and users, possibly anonymous an untrusted (e.g., Internet-facing web or mail server).
The affected configuration is default or ubiquitous. The attack can be performed manually and requires little skill or additional information gathering.
The 'race condition' is a lazy one (i.e., it is technically a race but easily winnable).
Authentication is not required to access and exploit the vulnerability.
There is total information disclosure, resulting in all system files being revealed. The
attacker is able to read all of the system's data (memory, files, etc.).
There is a total compromise of system integrity. There is a complete loss of system
protection, resulting in the entire system being compromised. The attacker is able to
modify any files on the target system.
There is a total shutdown of the affected resource. The attacker can render the
resource completely unavailable.