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Jan 12, 2021
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JS: better support for forms in js/xss-through-dom #4774

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3bad75d
better support for forms in js/xss-through-dom
erik-krogh Dec 3, 2020
47488f8
update test
erik-krogh Dec 3, 2020
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25 changes: 25 additions & 0 deletions javascript/ql/src/semmle/javascript/DOM.qll
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Expand Up @@ -298,6 +298,23 @@ module DOM {
)
}

/**
* A data flow node that might refer to some form.
* Either by a read like `document.forms[0]`, or a property read from `document` with some constant property-name.
* E.g. if `<form name="foobar">..</form>` exists, then `document.foobar` refers to that form.
*/
private DataFlow::SourceNode forms() {
result = documentRef().getAPropertyRead("forms").getAPropertyRead()
or
exists(DataFlow::PropRead read |
read = documentRef().getAPropertyRead() and
result = read
|
read.mayHavePropertyName(_) and
not read.mayHavePropertyName(getADomPropertyName())
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With the addition of this rule it seems we now consider all properties of document to be DOM value sources.

Maybe we should just express that in a more direct way.

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Are you suggesting that I put documentRef().getAPropertyRead(any(string s | not s = getADomPropertyName())) into DefaultRange?

I'm also using the forms predicate further down, so I would also like to keep the prop-read inside the forms predicate.

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I'm just saying that all of documentRef().getAPropertyRead() is now a DOM value source, but it's done in a very non-obvious, roundabout way, by unioning three sets:

  • all prop reads with a DOM property name
  • all prop reads with a non-DOM property name, and
  • all property reads with an unknown property name.

If we end up with all of them anyway, I'd just prefer to have documentRef().getAPropertyRead() be listed as an explicit case in DefaultRange. It's fine to keep the forms() predicate.

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documentRef().getAPropertyRead() is now a DOM value source

Hmmm. That turns out not to be the case.
I tried to add documentRef().getAPropertyRead(), but then the tests failed because document.location became a domValueRef.

domValueRef() does not contain documentRef(), so the property-read near the top of DefaultRange' does not refer to document`.

)
}

private class DefaultRange extends Range {
DefaultRange() {
this.asExpr().(VarAccess).getVariable() instanceof DOMGlobalVariable
Expand All @@ -317,6 +334,14 @@ module DOM {
or
this = domElementCollection()
or
this = forms()
or
// reading property `foo` - where a child has `name="foo"` - resolves to that child.
// We only look for such properties on forms/document, to avoid potential false positives.
exists(DataFlow::SourceNode form | form = [forms(), documentRef()] |
this = form.getAPropertyRead(any(string s | not s = getADomPropertyName()))
)
or
exists(JQuery::MethodCall call | this = call and call.getMethodName() = "get" |
call.getNumArgument() = 1 and
forex(InferredType t | t = call.getArgument(0).analyze().getAType() | t = TTNumber())
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2 changes: 2 additions & 0 deletions javascript/ql/test/library-tests/DOM/Customizations.expected
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Expand Up @@ -4,7 +4,9 @@ test_documentRef
test_locationRef
| customization.js:3:3:3:14 | doc.location |
test_domValueRef
| customization.js:4:3:4:20 | doc.getElementById |
| customization.js:4:3:4:28 | doc.get ... 'test') |
| nameditems.js:1:1:1:23 | documen ... entById |
| nameditems.js:1:1:1:30 | documen ... ('foo') |
| nameditems.js:1:1:2:19 | documen ... em('x') |
| tst.js:49:3:49:8 | window |
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10 changes: 10 additions & 0 deletions javascript/ql/test/library-tests/DOM/externs/externs.js
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Expand Up @@ -8,3 +8,13 @@ function EventTarget() {}

/** @type {EventTarget} */
var window;

/**
* @see http://dev.w3.org/html5/workers/
* @interface
* @extends {EventTarget}
*/
function WorkerGlobalScope() {}

/** @type {WorkerLocation} */
WorkerGlobalScope.prototype.location;
15 changes: 10 additions & 5 deletions javascript/ql/test/query-tests/Security/CWE-079/XssThroughDom/XssThroughDom.expected
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Expand Up @@ -44,8 +44,11 @@ nodes
| xss-through-dom.js:73:9:73:41 | selector |
| xss-through-dom.js:73:20:73:41 | $("inpu ... 0).name |
| xss-through-dom.js:73:20:73:41 | $("inpu ... 0).name |
| xss-through-dom.js:77:7:77:14 | selector |
| xss-through-dom.js:77:7:77:14 | selector |
| xss-through-dom.js:77:4:77:11 | selector |
| xss-through-dom.js:77:4:77:11 | selector |
| xss-through-dom.js:79:4:79:34 | documen ... t.value |
| xss-through-dom.js:79:4:79:34 | documen ... t.value |
| xss-through-dom.js:79:4:79:34 | documen ... t.value |
edges
| xss-through-dom.js:2:16:2:34 | $("textarea").val() | xss-through-dom.js:2:16:2:34 | $("textarea").val() |
| xss-through-dom.js:4:16:4:40 | $(".som ... .text() | xss-through-dom.js:4:16:4:40 | $(".som ... .text() |
Expand All @@ -61,10 +64,11 @@ edges
| xss-through-dom.js:61:30:61:69 | $(docum ... value") | xss-through-dom.js:61:30:61:69 | $(docum ... value") |
| xss-through-dom.js:64:30:64:40 | valMethod() | xss-through-dom.js:64:30:64:40 | valMethod() |
| xss-through-dom.js:71:11:71:32 | $("inpu ... 0).name | xss-through-dom.js:71:11:71:32 | $("inpu ... 0).name |
| xss-through-dom.js:73:9:73:41 | selector | xss-through-dom.js:77:7:77:14 | selector |
| xss-through-dom.js:73:9:73:41 | selector | xss-through-dom.js:77:7:77:14 | selector |
| xss-through-dom.js:73:9:73:41 | selector | xss-through-dom.js:77:4:77:11 | selector |
| xss-through-dom.js:73:9:73:41 | selector | xss-through-dom.js:77:4:77:11 | selector |
| xss-through-dom.js:73:20:73:41 | $("inpu ... 0).name | xss-through-dom.js:73:9:73:41 | selector |
| xss-through-dom.js:73:20:73:41 | $("inpu ... 0).name | xss-through-dom.js:73:9:73:41 | selector |
| xss-through-dom.js:79:4:79:34 | documen ... t.value | xss-through-dom.js:79:4:79:34 | documen ... t.value |
#select
| xss-through-dom.js:2:16:2:34 | $("textarea").val() | xss-through-dom.js:2:16:2:34 | $("textarea").val() | xss-through-dom.js:2:16:2:34 | $("textarea").val() | $@ is reinterpreted as HTML without escaping meta-characters. | xss-through-dom.js:2:16:2:34 | $("textarea").val() | DOM text |
| xss-through-dom.js:4:16:4:40 | $(".som ... .text() | xss-through-dom.js:4:16:4:40 | $(".som ... .text() | xss-through-dom.js:4:16:4:40 | $(".som ... .text() | $@ is reinterpreted as HTML without escaping meta-characters. | xss-through-dom.js:4:16:4:40 | $(".som ... .text() | DOM text |
Expand All @@ -80,4 +84,5 @@ edges
| xss-through-dom.js:61:30:61:69 | $(docum ... value") | xss-through-dom.js:61:30:61:69 | $(docum ... value") | xss-through-dom.js:61:30:61:69 | $(docum ... value") | $@ is reinterpreted as HTML without escaping meta-characters. | xss-through-dom.js:61:30:61:69 | $(docum ... value") | DOM text |
| xss-through-dom.js:64:30:64:40 | valMethod() | xss-through-dom.js:64:30:64:40 | valMethod() | xss-through-dom.js:64:30:64:40 | valMethod() | $@ is reinterpreted as HTML without escaping meta-characters. | xss-through-dom.js:64:30:64:40 | valMethod() | DOM text |
| xss-through-dom.js:71:11:71:32 | $("inpu ... 0).name | xss-through-dom.js:71:11:71:32 | $("inpu ... 0).name | xss-through-dom.js:71:11:71:32 | $("inpu ... 0).name | $@ is reinterpreted as HTML without escaping meta-characters. | xss-through-dom.js:71:11:71:32 | $("inpu ... 0).name | DOM text |
| xss-through-dom.js:77:7:77:14 | selector | xss-through-dom.js:73:20:73:41 | $("inpu ... 0).name | xss-through-dom.js:77:7:77:14 | selector | $@ is reinterpreted as HTML without escaping meta-characters. | xss-through-dom.js:73:20:73:41 | $("inpu ... 0).name | DOM text |
| xss-through-dom.js:77:4:77:11 | selector | xss-through-dom.js:73:20:73:41 | $("inpu ... 0).name | xss-through-dom.js:77:4:77:11 | selector | $@ is reinterpreted as HTML without escaping meta-characters. | xss-through-dom.js:73:20:73:41 | $("inpu ... 0).name | DOM text |
| xss-through-dom.js:79:4:79:34 | documen ... t.value | xss-through-dom.js:79:4:79:34 | documen ... t.value | xss-through-dom.js:79:4:79:34 | documen ... t.value | $@ is reinterpreted as HTML without escaping meta-characters. | xss-through-dom.js:79:4:79:34 | documen ... t.value | DOM text |
4 changes: 3 additions & 1 deletion javascript/ql/test/query-tests/Security/CWE-079/XssThroughDom/xss-through-dom.js
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Expand Up @@ -74,5 +74,7 @@
if (something()) {
selector = $("textarea").val || ''
}
$(selector); // NOT OK
$(selector); // NOT OK

$(document.my_form.my_input.value); // NOT OK
})();