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From YouTube: A First Look at the Security of Serverless Applications - Eduard Marin, Telefonica Research
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A First Look at the Security of Serverless Applications - Eduard Marin, Telefonica Research
Serverless computing is emerging as a new paradigm to deploy applications in the cloud, offering many advantages to cloud providers and their customers. Customers only have to be concerned about implementing their functions, leaving the management of the underlying hardware and software to cloud providers. Consequently, cloud providers are responsible for developing all security mechanisms to protect serverless applications from security attacks. Unfortunately, as serverless computing is a relatively new concept, its security has not yet been properly examined. In this talk, Eduard will shed light on the unique security threats and challenges of serverless platforms. Building on academic and industry research, Eduard will introduce the main types of security attacks against serverless applications along with the feasibility of realizing such attacks, and possible ways to mitigate them.
A
Good
afternoon
everyone,
my
name,
is
eduard
marin
and
I'm
a
researcher
at
telefonica
research.
Today
I
will
talk
about
the
security
of
serverless,
a
new
computing
paradigm
that
has
experienced
significant
growth
over
the
last
few
years
and
is
expected
to
become
the
dominant
pattern
for
cloud
computing
in
the
future.
A
Over
the
last
decade,
we
have
witnessed
significant
advancements
in
cloud
computing.
These
were
intended
to
simplify
the
development
and
management
of
applications,
as
well
as
reduce
the
cost
of
running
these
applications.
In
the
cloud
in
the
early
days
of
cloud
computing,
cloud
providers
gave
users
the
ability
to
port
their
monolithic
applications
to
the
cloud.
Virtual
machines
were
key
to
achieving
this,
offering
strong
isolation
while
providing
users
a
sense
of
having
an
infinite
amount
of
resources.
A
A
It
provided
lower
startup
times
compared
to
virtual
machines,
and
it
allowed
for
greater
efficiency,
but
it
also
came
with
some
important
limitations
as
all
containers
in
a
host
share.
The
same
kernel
containers
offer
weaker
isolation,
guarantees
than
virtual
machines.
Also,
software
developers
still
need
to
configure
and
manage
the
containers
themselves.
A
A
A
Scaling
of
applications
is
managed
directly
by
cloud
providers,
meaning
that
software
developers
don't
need
to
worry
about
when
and
how
the
application
needs
to
be
scaled
up
or
down.
Unlike
previous
approaches,
serverless
offers
a
pure
pay-per-use
model
where
users
pay
only
for
the
resources
they
consume.
Cloud
providers
such
as
amazon,
microsoft
and
google
are
already
offering
service
less
computing
services
to
their
customers.
Meanwhile,
several
open
source
serverless
platforms
have
also
been
developed
over
the
last
few
years
before
going
into
the
details
of
serverless
security.
A
A
If
a
function
is
triggered
many
times,
the
cloud
provider
can
opt
for
creating
new
instances
of
the
same
function
in
other
execution
environments
and
redirecting
some
requests
to
them.
Functions
typically
communicate
with
other
functions
and
also
with
other
cloud
services,
so,
for
example,
for
for
achieving
for
storage
purposes,
and
all
this
communication
is
done
via
standard
apis.
A
In
addition
to
this,
serverless
platforms
include
a
set
of
control,
plane
functionalities.
For
example.
One
could
be
an
authentication
server
that
authenticates
incoming
requests
before
passing
them
to
the
corresponding
functions.
Another
one
could
be
the
so-called
identity
and
access
management
component,
which
is
responsible
for
specifying
the
functions
and
cloud
services
that
each
function
can
can
access.
A
In
practice,
the
serverless
ecosystem
is
much
more
complex
than
that.
The
figure
shown
in
the
slide
is
a
simple
example
illustrating
a
real
state
website
using
serverless
functions.
Note
that
server
developers
can
choose
to
write
the
functions
themselves,
use
functions
from
third
parties
or
use
preparative
functions
for
which
they
pay.
Licensing
fees
also
note
that
only
a
subset
of
functions
can
communicate
with
the
outside
world.
A
Let's
now
try
to
understand
what
the
threat
model
of
serverless
in
any
serverless
platform
adversaries
can
try
to
steal,
sensitive
information
such
as
cryptographic,
keys
or
the
application
logic.
They
can
try
to
exfiltrate
data
control,
the
function's
execution
flow,
disrupt
other
applications,
run
applications
without
being
charged
or
even
worse,
associate
their
application
cost
to
other
users.
A
We
think
that
it's
important
to
model
cloud
providers
as
honest
but
curious
entities,
since
they
can
potentially
learn
sensitive
information
about
users
while
running
their
applications
with
the
increase
in
diversity
of
attacks
against
the
cloud
security
and
privacy
are
a
key
factor
for
the
widespread
adoption
of
surveillance
computing.
At
first
glance,
one
could
argue
that
serverless
computing
is
intrinsically
more
secure
than
its
predecessors.
A
A
For
example,
the
fact
that
functions
are
short-lived
makes
it
more
difficult
for
the
nurses
to
find
ways
to
persist
in
their
attacks.
The
bad
news
is
that
adversaries
have
already
proven
to
be
capable
of
bypassing
these
to
mounted
attacks,
but
despite
this,
it
is
positive
for
security
that
functions
run
for
such
a
short
period
of
time
with
serverless
security
is
a
shared
responsibility.
A
Software
developers
are
still
responsible
for
application
level
security,
but
the
rest
of
the
security
tasks
are
now
carried
out
by
cloud
providers.
This
is
expected
to
eliminate
the
number
of
attacks
against
serverless
applications
due
to
the
flexibility
and
elasticity
serverless
provides.
It
is
now
also
possible
to
mitigate
denial
of
service
attacks
that
aim
to
overload
the
server
where
the
application
runs.
A
A
There
are
three
main
reasons
why
the
attack
surface
of
serverless
is
larger
than
in
previous
approaches.
First
functions
are
even
event
driven,
which
means
that
they
can
be
triggered
by
many
types
of
internal
and
external
event,
sources
with
multiple
formats
and
encodings.
This
clearly
opens
the
door
for
aggressors.
To
perform.
Many
attacks
as
functions
are
stateless
and
are
intended
to
perform
a
single
task.
They
are
required
to
constantly
interact
with
other
functions
and
cloud
services
to
realize
more
complex
functionalities.
A
Finally,
serverless
platforms
include
several
new
components
and
cloud
services,
many
of
which
are
shared
across
users.
These
may
lead
to
new
forms
of
cover
and
side
channels
that
can
result
in
attacks
aimed
to
retrieve
sensitive
data
or
allow
malicious
functions
to
communicate
with
each
other
without
the
cloud
provider
noticing
it.
A
Ideally,
cloud
providers
would
like
to
develop
serverless
platforms
that
jolly
maximize
security
and
performance
in
their
infrastructures
and
their
customers
applications,
while
keeping
their
cost
as
low
as
possible.
In
practice,
however,
experience
has
shown
that
cloud
providers
often
sacrifice
some
security
to
be
able
to
accommodate
more
users
and
to
provide
greater
performance
to
their
users
applications.
A
One
clear
example
is
on
the
selection
of
the
sandboxing
mechanisms,
as
we
explained
before,
with
the
example
of
the
bm
and
the
container.
Another
example
is
on
whether
to
use
cold
or
warm
containers
called
containers
refer
to
containers
that
are
used
only
once.
The
problem
with
cold
containers
is
that
their
booting
time
is
often
similar
to
the
time
it
takes
to
execute
the
function
itself.
A
Therefore,
the
latency
introduced
when
booting
can
significantly
affect
the
function's
performance.
In
addition
to
this
cloud
providers,
don't
build
users
based
on
the
booting
time
of
their
functions.
So,
of
course,
they
want
to
minimize
it
as
much
as
possible
to
solve
this
problem.
Cloud
providers
have
started
to
use
so-called
worm
containers.
A
A
Another
example
has
to
do
with
the
process
of
assigning
functions
to
the
host.
This
can
be
done
using
deterministic
of
randomized
scheduling,
algorithms,
while
deterministic
scheduling
algorithms
can
lead
to
a
more
optimal
use
of
resources
and
less
communication.
Overhead
randomized
algorithms
can
offer
stronger
protection
against
attacks
that
exploit
residency
with
the
victim.
All
these
examples
show
that
there
is
a
need
to
achieve
a
good
balance
between
security
and
performance.
A
One
of
the
main
advantages
of
serverless
is
that
cloud
providers
are
now
only
responsible
for
conducting
all
operational
infrastructure
tasks,
including
those
aim
to
protect
their
infrastructures
and
the
workloads
running
on
them
from
internal
and
external
threats
at
first.
This
is
expected
to
reduce
the
number
of
attacks
against
severus
platforms,
yet
this
can
also
lead
software
developers
to
ignore
security
in
their
applications
and
to
make
realistic,
unrealistic
assumptions
about
the
security
measures
in
place.
This
could
create
a
false
sense
of
security
to
make
things
worse.
A
A
Let's
now
talk
about
the
main
attacks
against
serverless,
we
have
identified
three
three
main
classes.
One
of
them
is
related
to
their
application
level
attacks
the
other
one
is
more
specific
to
to
serverless,
and
the
last
one
is
about
hardware
attacks
such
as
microarchitectural
type
of
attacks
like
meltdown
or
raw
hammer
type
of
attacks.
Due
to
the
time
constraints,
I
will
not
cover
hardware
attacks
in
this.
In
this
talk,
o
wasp
has
recently
released
a
report
explaining
the
top
10
security
threats
for
surveillance
allocations.
You
can
see
them
on
the
on
the
slide.
A
A
Additionally,
software
developers
should
also
follow
the
principle
of
least
privilege,
because
functions
will
eventually
be
compromised
and
once
a
function
is
compromised,
the
goal
should
be
is
to
to
reduce
the
the
amount
of
damage
that
the
bursary
can
do
and,
finally,
to
prevent
this
kind
of
attacks.
It's
also
it's
very
important
to
secure
data
both
at
rest
and
in
transit
to
secure
data
address
one
can
use
cloud
services
and
to
secure
data
in
transit.
For
example,
one
can
use
strong
cryptographic
protocols
such
as
tls.
A
Let's
now
go
a
little
bit
more
in
depth
on
the
surface
specific
type
of
attacks.
One
of
them
is
the
the
one
so-called
resource
exhaustion
attacks.
The
goal
of
this
kind
of
attack
is
to
over
utilize
the
resources
of
the
victim
to
either
disrupt
the
service
or
to
impose
excessive
financial
loads
to
the
victim
so
basically
to
perform
so-called
denial
of
wallet
attacks
in
such
a
complex
and
dynamic
type
of
system.
Adversaries
can
also
try
to
leverage
inconsistencies
in
functions
and
cloud
services.
A
This
remains
unexplored
so
far,
but
I
think
it's
an
interesting
avenue
for
for
research
site
channel
attacks
are
also
very
important
in
serverless
platforms.
They
can
come
with
different
flavors.
There
are
different
ways.
These
kind
of
attacks
can
be
can
be
achieved.
One
of
them
is
based
on,
for
example,
the
access
patterns
or
timing
information.
A
A
Finally,
I
want
to
refer
to
you
to
to
a
paper
on
serverless
security
that
explores
in
more
depth
all
the
of
the
different
aspects
that
I've
been
discussing
in
this
presentation.
You
can
find
it
in
my
personal
website,
and
I
also
want
to
to
mention
that
we're
organizing
a
workshop
on
serverless
for
mobile
networks.
You
can
also
see
the
website
there
and
that's
all
from
my
site,
if
you
have
any
questions
I'll,
be
very
happy
to
take
them.
Thank
you.