/usr/lib/libei_st.a is in erlang-dev 1:14.b.4-dfsg-1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/erlang/lib/erl_interface-3.7.5/lib/libei_st.a
/usr/lib/erlang/lib/erl_interface-3.7.5/lib/libei_st.a