Input validation

An issue was discovered on Securifi Almond, Almond+, and Almond 2015 devices with firmware AL-R096. The device provides a UPnP functionality for devices to interface with the router and interact with the device. It seems that the “NewInMessage” SOAP parameter passed with a huge payload results in crashing the process. If the firmware version AL-R096 is dissected using binwalk tool, we obtain a cpio-root archive which contains the filesystem set up on the device that contains all the binaries. The binary “miniupnpd” is the one that has the vulnerable function that receives the values sent by the SOAP request. If we open this binary in IDA-pro we will notice that this follows a MIPS little endian format. The function WscDevPutMessage at address 0x0041DBB8 in IDA pro is identified to be receiving the values sent in the SOAP request. The SOAP parameter “NewInMesage” received at address 0x0041DC30 causes the miniupnpd process to finally crash when a second request is sent to the same process.