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Python: Split modelling of query operators

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`$where` and `$function` behave quite differently.
This commit is contained in:
Rasmus Lerchedahl Petersen
2023-09-11 15:54:00 +02:00
parent 154a36934d
commit d9f63e1ed3
2 changed files with 29 additions and 11 deletions
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31
python/ql/lib/semmle/python/frameworks/NoSQL.qll
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@@ -99,9 +99,6 @@ private module NoSql {
] ]
} }
/** Gets the name of a mongo query operator that will interpret JavaScript. */
private string mongoQueryOperator() { result in ["$where", "$function"] }
/** /**
* Gets a reference to a `Mongo` collection method call * Gets a reference to a `Mongo` collection method call
* *
@@ -125,12 +122,34 @@ private module NoSql {
override predicate vulnerableToStrings() { none() } override predicate vulnerableToStrings() { none() }
} }
private class MongoCollectionQueryOperator extends API::CallNode, NoSqlQuery::Range { /** The `$where` query operator executes a string as JavaScript. */
private class WhereQueryOperator extends API::CallNode, NoSqlQuery::Range {
DataFlow::Node query; DataFlow::Node query;
MongoCollectionQueryOperator() { WhereQueryOperator() {
this = mongoCollection().getMember(mongoCollectionMethodName()).getACall() and this = mongoCollection().getMember(mongoCollectionMethodName()).getACall() and
query = this.getParameter(0).getSubscript(mongoQueryOperator()).asSink() query = this.getParameter(0).getSubscript("$where").asSink()
}
override DataFlow::Node getQuery() { result = query }
override predicate interpretsDict() { none() }
override predicate vulnerableToStrings() { any() }
}
/** The `$function` query operator executes its `body` string as JavaScript. */
private class FunctionQueryOperator extends API::CallNode, NoSqlQuery::Range {
DataFlow::Node query;
FunctionQueryOperator() {
this = mongoCollection().getMember(mongoCollectionMethodName()).getACall() and
query =
this.getParameter(0)
.getASubscript*()
.getSubscript("$function")
.getSubscript("body")
.asSink()
} }
override DataFlow::Node getQuery() { result = query } override DataFlow::Node getQuery() { result = query }

9
python/ql/test/query-tests/Security/CWE-943-NoSqlInjection/PoC/server.py
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@@ -46,30 +46,29 @@ def by_where():
post = posts.find_one({'$where': 'this.author === "'+author+'"'}) # $ result=BAD post = posts.find_one({'$where': 'this.author === "'+author+'"'}) # $ result=BAD
return show_post(post, author) return show_post(post, author)
@app.route('/byFunction', methods=['GET']) @app.route('/byFunction', methods=['GET'])
def by_function(): def by_function():
author = request.args['author'] author = request.args['author']
search = { search = {
"body": 'function(author) { return(author === "'+author+'") }', "body": 'function(author) { return(author === "'+author+'") }', # $ result=BAD
"args": [ "$author" ], "args": [ "$author" ],
"lang": "js" "lang": "js"
} }
# Use `" | "a" === "a` as author # Use `" | "a" === "a` as author
# making the query `this.author === "" | "a" === "a"` # making the query `this.author === "" | "a" === "a"`
# Found by http://127.0.0.1:5000/byFunction?author=%22%20|%20%22a%22%20===%20%22a # Found by http://127.0.0.1:5000/byFunction?author=%22%20|%20%22a%22%20===%20%22a
post = posts.find_one({'$expr': {'$function': search}}) # $ MISING: result=BAD post = posts.find_one({'$expr': {'$function': search}}) # $ result=BAD
return show_post(post, author) return show_post(post, author)
@app.route('/byFunctionArg', methods=['GET']) @app.route('/byFunctionArg', methods=['GET'])
def by_function_arg(): def by_function_arg():
author = request.args['author'] author = request.args['author']
search = { search = {
"body": 'function(author, target) { return(author === target) }', "body": 'function(author, target) { return(author === target) }', # $ result=OK
"args": [ "$author", author ], "args": [ "$author", author ],
"lang": "js" "lang": "js"
} }
post = posts.find_one({'$expr': {'$function': search}}) # $ result=OK post = posts.find_one({'$expr': {'$function': search}}) # $ SPURIOUS: result=BAD
return show_post(post, author) return show_post(post, author)
@app.route('/', methods=['GET']) @app.route('/', methods=['GET'])