class TestSensitiveAccess(unittest.TestCase):
"""Test class for single value condition too permissive auditor"""
example_policy_string = """
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"s3:GetObject"
],
"Resource": "arn:aws:s3:::secretbucket/*",
"Condition": {
"ForAllValues:StringEquals": {
"aws:ResourceTag/Tag": [
"Value"
]
}
}
}
]
}
"""
policy = analyze_policy_string(example_policy_string,
include_community_auditors=True)
assert_equal(policy.finding_ids,
set(["SINGLE_VALUE_CONDITION_TOO_PERMISSIVE"]))
def test_resource_effectively_star(self):
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "CloudtrailReadTrail",
"Effect": "Allow",
"Action": [
"cloudtrail:GetEventSelectors",
"cloudtrail:PutEventSelectors"
],
"Resource": [
"arn:*:cloudtrail:*:*:trail/*"
]
}
]
}""")
assert_equal(
policy.finding_ids,
set(["RESOURCE_EFFECTIVELY_STAR"]),
"Resource policy spans all Cloudtrails even without an asterisk.",
)
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "CloudtrailReadTrail",
"Effect": "Allow",
"Action": [
"cloudtrail:GetEventSelectors",
"cloudtrail:PutEventSelectors"
],
"Resource": [
"arn:aws:cloudtrail:us-east-1:000000000000:trail/*"
]
}
]
}""")
assert_equal(
policy.finding_ids,
set(),
"Resource policy is scoped by AWS partition, account and region and is therefore not 'STAR'.",
)
def test_resource_bad(self):
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:listallmybuckets",
"Resource": "s3"}}""")
assert_equal(len(policy.findings), 1)
def test_analyze_policy_string_no_action(self):
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Resource": "*"}}""")
assert_false(
len(policy.findings) == 0, "Policy does not have an Action")
def test_notprincipal_allow(self):
# NotPrincipal is OK with Effect: Deny. This explcitly omits these
# users from the list of Principals denied access to this resource
# This example is taken from https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_notprincipal.html#specifying-notprincipal
policystr = """{
"Version": "2012-10-17",
"Statement": [{
"Effect": "Deny",
"NotPrincipal": {"AWS": [
"arn:aws:iam::444455556666:user/Bob",
"arn:aws:iam::444455556666:root"
]},
"Action": "s3:*",
"Resource": [
"arn:aws:s3:::BUCKETNAME",
"arn:aws:s3:::BUCKETNAME/*"
]
}]
}"""
policy = analyze_policy_string(policystr,
include_community_auditors=True)
assert_equal(policy.finding_ids, set())
# This implicitly allows everyone _except_ Bob to access BUCKETNAME!
policystr = """{
"Version": "2012-10-17",
"Statement": [{
"Effect": "Allow",
"NotPrincipal": {"AWS": [
"arn:aws:iam::444455556666:user/Bob",
]},
"Action": "s3:*",
"Resource": [
"arn:aws:s3:::BUCKETNAME",
"arn:aws:s3:::BUCKETNAME/*"
]
}]
}"""
policy = analyze_policy_string(policystr,
include_community_auditors=True)
assert_equal(policy.finding_ids,
S3_STAR_FINDINGS | {"NOTPRINCIPAL_WITH_ALLOW"})
def test_resource_policy_privilege_escalation(self):
# This policy is actually granting essentially s3:* due to the ability to put a policy on a bucket
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": ["s3:GetObject", "s3:PutBucketPolicy"],
"Resource": "*"
}}""")
assert_false(
len(policy.findings) == 0, "Resource policy privilege escalation")
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": [
{
"Action": [
"s3:ListBucket",
"s3:Put*",
"s3:Get*",
"s3:*MultipartUpload*"
],
"Resource": [
"*"
],
"Effect": "Allow"
},
{
"Action": [
"s3:*Policy*",
"sns:*Permission*",
"sns:*Delete*",
"s3:*Delete*",
"sns:*Remove*"
],
"Resource": [
"*"
],
"Effect": "Deny"
}
]}""")
assert_false(
len(policy.findings) == 0,
"Resource policy privilege escalation across two statement",
)
def test_condition_multiple(self):
# Both good
policy = analyze_policy_string(
"""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:listbucket",
"Resource": "arn:aws:s3:::bucket-name",
"Condition": {
"DateGreaterThan" :{"aws:CurrentTime" : "2019-07-16T12:00:00Z"},
"StringEquals": {"s3:prefix":["home/${aws:username}/*"]}
} }}"""
)
assert_equal(len(policy.findings), 0)
# First bad
policy = analyze_policy_string(
"""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:listbucket",
"Resource": "arn:aws:s3:::bucket-name",
"Condition": {
"DateGreaterThan" :{"aws:CurrentTime" : "bad"},
"StringEquals": {"s3:prefix":["home/${aws:username}/*"]}
} }}"""
)
assert_false(len(policy.findings) == 0, "First condition is bad")
# Second bad
policy = analyze_policy_string(
"""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:listbucket",
"Resource": "arn:aws:s3:::bucket-name",
"Condition": {
"DateGreaterThan" :{"aws:CurrentTime" : "2019-07-16T12:00:00Z"},
"StringEquals": {"s3:x":["home/${aws:username}/*"]}
} }}"""
)
assert_false(len(policy.findings) == 0, "Second condition is bad")
def test_resource_good(self):
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:getobject",
"Resource": "arn:aws:s3:::my_corporate_bucket/*"}}""")
print(policy.findings)
assert_equal(len(policy.findings), 0)
def test_condition_mismatch(self):
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": ["ec2:*", "s3:*"],
"Resource": "*",
"Condition": {"StringNotEquals": {"iam:ResourceTag/status":"prod"}} }}"""
)
assert_false(len(policy.findings) == 0, "Condition mismatch")
def test_condition(self):
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:listbucket",
"Resource": "arn:aws:s3:::bucket-name",
"Condition": {"DateGreaterThan" :{"aws:CurrentTime" : "2019-07-16T12:00:00Z"}} }}"""
)
assert_equal(len(policy.findings), 0)
def test_condition_operator(self):
policy = analyze_policy_string(
"""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:listbucket",
"Resource": "arn:aws:s3:::bucket-name",
"Condition": {"StringEqualsIfExists": {"s3:prefix":["home/${aws:username}/*"]}} }}""",
ignore_private_auditors=True,
)
assert_equal(policy.finding_ids, set())
policy = analyze_policy_string(
"""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:listbucket",
"Resource": "arn:aws:s3:::bucket-name",
"Condition": {"bad": {"s3:prefix":["home/${aws:username}/*"]}} }}""",
ignore_private_auditors=True,
)
assert_equal(
policy.finding_ids,
set(["UNKNOWN_OPERATOR", "MISMATCHED_TYPE"]),
"Unknown operator",
)
policy = analyze_policy_string(
"""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:listbucket",
"Resource": "arn:aws:s3:::bucket-name",
"Condition": {"NumericEquals": {"s3:prefix":["home/${aws:username}/*"]}} }}""",
ignore_private_auditors=True,
)
assert_equal(
policy.finding_ids, set(["MISMATCHED_TYPE"]), "Operator type mismatch"
)
def test_analyze_policy_string_opposites(self):
# Policy contains Action and NotAction
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:listallmybuckets",
"NotAction": "s3:listallmybuckets",
"Resource": "*"}}""")
assert_false(
len(policy.findings) == 0, "Policy contains Action and NotAction")
def test_analyze_policy_string_invalid_sid(self):
policy = analyze_policy_string(
"""{
"Version": "2012-10-17",
"Statement": {
"Sid": "Statement With Spaces And Special Chars!?",
"Effect": "Allow",
"Action": "s3:listallmybuckets",
"Resource": "*"}}"""
)
assert_false(len(policy.findings) == 0, "Policy statement has invalid Sid")
def test_condition_bad_key(self):
policy = analyze_policy_string(
"""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:listbucket",
"Resource": "arn:aws:s3:::bucket-name",
"Condition": {"DateGreaterThan" :{"bad" : "2019-07-16T12:00:00Z"}} }}"""
)
assert_false(len(policy.findings) == 0, "Policy has bad key in Condition")
def test_bad_mfa_condition(self):
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "*",
"Resource": "*",
"Condition": {"Bool": {"aws:MultiFactorAuthPresent":"false"}}
}}""")
assert_false(
len(policy.findings) == 0, "Policy contains bad MFA check")
def check_policy(self, name, document):
policy = parliament.analyze_policy_string(json.dumps(document))
for permission in REQUIRED_PERMISSIONS:
if policy.get_allowed_resources(*permission.split(":")) != ["*"]:
self._failure(
f"Discarding Instance Policy {name}\n\tMissing permission {permission}"
)
return False
self._success(f"Found Valid SSM Instance Policy {name}")
return True
def test_analyze_policy_string_no_action(self):
policy = analyze_policy_string(
"""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Resource": "*"}}""",
ignore_private_auditors=True,
)
assert_equal(policy.finding_ids, set(["MALFORMED"]),
"Policy does not have an Action")
def test_notresource_allow(self):
# NotResource is OK with Effect: Deny. This denies access to
# all S3 buckets except Payroll buckets. This example is taken from
# https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_notresource.html
policystr = """{
"Version": "2012-10-17",
"Statement": {
"Effect": "Deny",
"Action": "s3:*",
"NotResource": [
"arn:aws:s3:::HRBucket/Payroll",
"arn:aws:s3:::HRBucket/Payroll/*"
]
}
}"""
policy = analyze_policy_string(policystr,
include_community_auditors=True)
assert_equal(policy.finding_ids, set())
# According to AWS documentation, "This statement is very dangerous,
# because it allows all actions in AWS on all resources except the
# HRBucket S3 bucket." See:
# https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_notresource.html#notresource-element-combinations
policystr = """{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:*",
"NotResource": [
"arn:aws:s3:::HRBucket/Payroll",
"arn:aws:s3:::HRBucket/Payroll/*"
]
}
}"""
policy = analyze_policy_string(policystr,
include_community_auditors=True)
assert_equal(policy.finding_ids,
S3_STAR_FINDINGS | {"NOTRESOURCE_WITH_ALLOW"})
def test_condition_action_specific_bad_type(self):
# s3:signatureage requires a number
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:listbucket",
"Resource": "arn:aws:s3:::bucket-name",
"Condition": {"StringEquals": {"s3:signatureage":"bad"}} }}""")
print(policy.findings)
assert_false(
len(policy.findings) == 0, 'Wrong type, "bad" should be a number')
def test_analyze_policy_string_correct_multiple_statements_and_actions(
self):
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": [{
"Effect": "Allow",
"Action": "s3:listallmybuckets",
"Resource": "*"},
{
"Effect": "Allow",
"Action": "iam:listusers",
"Resource": "*"}]}""")
assert_equal(len(policy.findings), 0)
def validate_file(filename):
with (open(filename, 'r')) as file:
tf = hcl2.load(file)
findings = []
# Validate data.aws_iam_policy_document
for policy_document in filter(
lambda x: x.get('aws_iam_policy_document', None),
tf.get('data', [])):
iam_statements = []
policy_name = list(
policy_document['aws_iam_policy_document'].keys())[0]
for statement_data in policy_document['aws_iam_policy_document'][
policy_name]['statement']:
# Don't check assume role policies; these will have spurious findings for
# "Statement contains neither Resource nor NotResource"
actions = statement_data.get('actions')[0]
if actions == ['sts:AssumeRole'
] or actions == ['sts:AssumeRoleWithSAML']:
continue
iam_statements.append(mock_iam_statement_from_tf(statement_data))
policy_string = policy_template.format(
iam_statements=json.dumps(iam_statements))
findings += parliament.analyze_policy_string(policy_string).findings
# Validate resource.aws_iam_policy
for policy in filter(lambda x: x.get('aws_iam_policy', None),
tf.get('resource', [])):
try:
policy_string = policy['aws_iam_policy']['policy']['policy'][0]
except KeyError:
continue
findings += parliament.analyze_policy_string(policy_string).findings
return findings
def test_analyze_policy_string_correct_simple(self):
policy = analyze_policy_string(
"""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:listallmybuckets",
"Resource": "*"}}""",
ignore_private_auditors=True,
)
assert_equal(
policy.finding_ids, set(),
)
def test_analyze_policy_string_invalid_sid(self):
policy = analyze_policy_string(
"""{
"Version": "2012-10-17",
"Statement": {
"Sid": "Statement With Spaces And Special Chars!?",
"Effect": "Allow",
"Action": "s3:listallmybuckets",
"Resource": "*"}}""",
ignore_private_auditors=True,
)
assert_equal(policy.finding_ids, set(["INVALID_SID"]),
"Policy statement has invalid Sid")
def test_resource_policy_privilege_escalation_at_bucket_level(self):
policy = analyze_policy_string(
"""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": ["s3:GetObject", "s3:PutBucketPolicy"],
"Resource": ["arn:aws:s3:::bucket", "arn:aws:s3:::bucket/*"]
}}""",
ignore_private_auditors=True,
)
assert_equal(
policy.finding_ids,
set(["RESOURCE_POLICY_PRIVILEGE_ESCALATION"]),
"Resource policy privilege escalation",
)
policy = analyze_policy_string(
"""{
"Version": "2012-10-17",
"Statement": [{
"Effect": "Allow",
"Action": ["s3:*Bucket*", "s3:*Object*"],
"Resource": ["arn:aws:s3:::bucket1", "arn:aws:s3:::bucket1/*"]
},
{
"Effect": "Allow",
"Action": ["s3:*Object"],
"Resource": ["arn:aws:s3:::bucket2/*"]
}]}""",
ignore_private_auditors=True,
)
# There is one finding for "No resources match for s3:ListAllMyBuckets which requires a resource format of *"
assert_equal(
policy.finding_ids,
set(["RESOURCE_MISMATCH"]),
"Buckets do not match so no escalation possible",
)
def test_condition_type_unqoted_bool(self):
policy = analyze_policy_string(
"""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "kms:CreateGrant",
"Resource": "*",
"Condition": {"Bool": {"kms:GrantIsForAWSResource": true}} }}""",
ignore_private_auditors=True,
)
assert_equal(
policy.finding_ids, set(["RESOURCE_STAR"]),
)
def test_resource_with_sub(self):
policy = analyze_policy_string("""{
"Version":"2012-10-17",
"Statement":[
{
"Sid":"AddPerm",
"Effect":"Allow",
"Principal": "*",
"Action":["ssm:PutParameter"],
"Resource":[{"Fn::Sub": "arn:aws:ssm:*:${AWS::AccountId}:*"}]
}
]
}""")
assert_equal(policy.finding_ids, {"INVALID_ARN"})
def test_analyze_policy_string_multiple_statements_one_bad(self):
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": [{
"Effect": "Allow",
"Action": "s3:listallmybuckets",
"Resource": "*"},
{
"Effect": "Allow",
"Action": ["iam:listusers", "iam:list"],
"Resource": "*"}]}""")
assert_false(
len(policy.findings) == 0,
"Policy with multiple statements has one bad")
def test_analyze_policy_string_MFA_formatting(self):
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": {
"Sid": "AllowManageOwnVirtualMFADevice",
"Effect": "Allow",
"Action": [
"iam:CreateVirtualMFADevice",
"iam:DeleteVirtualMFADevice"
],
"Resource": "arn:aws:iam::*:mfa/${aws:username}"
}
}""")
assert_equal(policy.finding_ids, set([]), "Policy is valid")
def test_condition_action_specific(self):
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:listbucket",
"Resource": "arn:aws:s3:::bucket-name",
"Condition": {"StringEquals": {"s3:prefix":["home/${aws:username}/*"]}} }}"""
)
assert_equal(len(policy.findings), 0)
# The key s3:x-amz-storage-class is not allowed for ListBucket,
# but is for other S3 actions
policy = analyze_policy_string("""{
"Version": "2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "s3:listbucket",
"Resource": "arn:aws:s3:::bucket-name",
"Condition": {"StringEquals": {"s3:x-amz-storage-class":"bad"}} }}""")
assert_false(
len(policy.findings) == 0,
"Policy uses key that cannot be used for the action",
)
def test_bad_principals(self):
# Good principal
policy = analyze_policy_string("""{
"Version":"2012-10-17",
"Statement":[
{
"Sid":"AddPerm",
"Effect":"Allow",
"Principal": "*",
"Action":["s3:GetObject"],
"Resource":["arn:aws:s3:::examplebucket/*"]
}
]
}""")
assert_true(len(policy.findings) == 0, "Basic S3 bucket policy")
