Command and Control
curl supports the
-t command line option, known as
CURLOPT_TELNETOPTIONSin libcurl. This rarely used option is used to send variable=content pairs toTELNET servers.Due to flaw in the option parser for sending
NEW_ENV variables, libcurlcould be made to pass on uninitialized data from a stack based buffer to theserver. Therefore potentially revealing sensitive internal information to theserver using a clear-text network protocol.This could happen because curl did not call and use sscanf() correctly whenparsing the string provided by the application.