2018-10-17 02:00:00
talos
PUBLISHED
Devices in the Linksys ESeries line of routers (Linksys E1200 Firmware Version 2.0.09 and Linksys E2500 Firmware Version 3.0.04) are susceptible to OS command injection vulnerabilities due to improper filtering of data passed to and retrieved from NVRAM. Data entered into the Router Name input field through the web portal is submitted to apply.cgi as the value to the machine_name POST parameter. When the preinit binary receives the SIGHUP signal, it enters a code path that continues until it reaches offset 0x0042B5C4 in the start_lltd function. Within the start_lltd function, a nvram_get call is used to obtain the value of the user-controlled machine_name NVRAM entry. This value is then entered directly into a command intended to write the host name to a file and subsequently executed.