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Detect empty string socket binds in B104 #1438

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24 changes: 20 additions & 4 deletions bandit/plugins/general_bind_all_interfaces.py
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Original file line number Diff line number Diff line change
Expand Up @@ -9,8 +9,8 @@

Binding to all network interfaces can potentially open up a service to traffic
on unintended interfaces, that may not be properly documented or secured. This
plugin test looks for a string pattern "0.0.0.0" that may indicate a hardcoded
binding to all network interfaces.
plugin test looks for a string pattern "0.0.0.0" or a bind address of "" that
may indicate a hardcoded binding to all network interfaces.

:Example:

Expand All @@ -22,7 +22,8 @@
Location: ./examples/binding.py:4
3 s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
4 s.bind(('0.0.0.0', 31137))
5 s.bind(('192.168.0.1', 8080))
5 s.bind(('', 31137))
6 s.bind(('192.168.0.1', 8080))

.. seealso::

Expand All @@ -40,7 +41,7 @@
from bandit.core import test_properties as test


@test.checks("Str")
@test.checks("Str", "Call")
@test.test_id("B104")
def hardcoded_bind_all_interfaces(context):
if context.string_val == "0.0.0.0": # nosec: B104
Expand All @@ -50,3 +51,18 @@ def hardcoded_bind_all_interfaces(context):
cwe=issue.Cwe.MULTIPLE_BINDS,
text="Possible binding to all interfaces.",
)

if context.call_function_name != "bind":
return

bind_arg = context.get_call_arg_at_position(0)
if not isinstance(bind_arg, tuple) or not bind_arg:
return

if bind_arg[0] == "":
return bandit.Issue(
severity=bandit.MEDIUM,
confidence=bandit.MEDIUM,
cwe=issue.Cwe.MULTIPLE_BINDS,
text="Possible binding to all interfaces.",
)
2 changes: 2 additions & 0 deletions examples/binding.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2,4 +2,6 @@

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(('0.0.0.0', 31137))
s.bind(('', 31137))
s.bind(('192.168.0.1', 8080))
s.bind(('127.0.0.1', 8080))
6 changes: 3 additions & 3 deletions tests/functional/test_functional.py
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Original file line number Diff line number Diff line change
Expand Up @@ -110,10 +110,10 @@ def check_metrics(self, example_script, expect):
self.assertEqual(expected, m["_totals"][label])

def test_binding(self):
"""Test the bind-to-0.0.0.0 example."""
"""Test bind-to-all-interfaces examples."""
expect = {
"SEVERITY": {"UNDEFINED": 0, "LOW": 0, "MEDIUM": 1, "HIGH": 0},
"CONFIDENCE": {"UNDEFINED": 0, "LOW": 0, "MEDIUM": 1, "HIGH": 0},
"SEVERITY": {"UNDEFINED": 0, "LOW": 0, "MEDIUM": 2, "HIGH": 0},
"CONFIDENCE": {"UNDEFINED": 0, "LOW": 0, "MEDIUM": 2, "HIGH": 0},
}
self.check_example("binding.py", expect)

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