Impact
The use of String.to_atom/1 in PowAssent is susceptible to denial of service attacks. In PowAssent.Phoenix.AuthorizationController a value is fetched from the user provided params, and String.to_atom/1 is used to convert the binary value to an atom so it can be used to fetch the provider configuration value. This is unsafe as it's user provided data, and can be used to fill up the whole atom table of ~1M which will cause the app to crash.
Workarounds
A plug can be used to validate conn.params["provider"] before it reaches the PowAssent.Phoenix.AuthorizationController.
References
http://erlang.org/doc/efficiency_guide/commoncaveats.html#list_to_atom-1
Impact
The use of
String.to_atom/1in PowAssent is susceptible to denial of service attacks. InPowAssent.Phoenix.AuthorizationControllera value is fetched from the user provided params, andString.to_atom/1is used to convert the binary value to an atom so it can be used to fetch the provider configuration value. This is unsafe as it's user provided data, and can be used to fill up the whole atom table of ~1M which will cause the app to crash.Workarounds
A plug can be used to validate
conn.params["provider"]before it reaches thePowAssent.Phoenix.AuthorizationController.References
http://erlang.org/doc/efficiency_guide/commoncaveats.html#list_to_atom-1