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Merged
semmle-qlci merged 4 commits into from Sep 14, 2018
Merged

JS: add additional array-specific taint steps #192

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ea37665
JS: move array-specific taint steps to separate class
Sep 11, 2018
763da72
JS: modernize old array taint steps
Sep 11, 2018
4c13e6b
JS: add additional array-specific taint steps
Sep 11, 2018
cb2bd9e
JS: change notes for additional array taint steps
Sep 13, 2018
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2 changes: 2 additions & 0 deletions change-notes/1.19/analysis-javascript.md
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Expand Up @@ -2,6 +2,8 @@

## General improvements

* Modelling of taint flow through array operations has been improved. This may give additional results for the security queries.

## New queries

| **Query** | **Tags** | **Purpose** |
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92 changes: 62 additions & 30 deletions javascript/ql/src/semmle/javascript/dataflow/TaintTracking.qll
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Expand Up @@ -185,38 +185,15 @@ module TaintTracking {

override predicate step(DataFlow::Node pred, DataFlow::Node succ) {
succ = this and
(
exists (Expr e, Expr f | e = this.asExpr() and f = pred.asExpr() |
// arrays with tainted elements and objects with tainted property names are tainted
e.(ArrayExpr).getAnElement() = f or
exists (Property prop | e.(ObjectExpr).getAProperty() = prop |
prop.isComputed() and f = prop.getNameExpr()
)
or
// awaiting a tainted expression gives a tainted result
e.(AwaitExpr).getOperand() = f
exists (Expr e, Expr f | e = this.asExpr() and f = pred.asExpr() |
// arrays with tainted elements and objects with tainted property names are tainted
e.(ArrayExpr).getAnElement() = f or
exists (Property prop | e.(ObjectExpr).getAProperty() = prop |
prop.isComputed() and f = prop.getNameExpr()
)
or
// `array.map(function (elt, i, ary) { ... })`: if `array` is tainted, then so are
// `elt` and `ary`; similar for `forEach`
exists (MethodCallExpr m, Function f, int i, SimpleParameter p |
(m.getMethodName() = "map" or m.getMethodName() = "forEach") and
(i = 0 or i = 2) and
m.getArgument(0).analyze().getAValue().(AbstractFunction).getFunction() = f and
p = f.getParameter(i) and
this = DataFlow::parameterNode(p) and
pred.asExpr() = m.getReceiver()
)
or
// `array.map` with tainted return value in callback
exists (MethodCallExpr m, Function f |
this.asExpr() = m and
m.getMethodName() = "map" and
m.getArgument(0) = f and // Require the argument to be a closure to avoid spurious call/return flow
pred = f.getAReturnedExpr().flow())
or
// `array.push(e)`: if `e` is tainted, then so is `array`
succ.(DataFlow::SourceNode).getAMethodCall("push").getAnArgument() = pred
// awaiting a tainted expression gives a tainted result
e.(AwaitExpr).getOperand() = f
)
or
// reading from a tainted object yields a tainted result
Expand All @@ -233,6 +210,61 @@ module TaintTracking {
}
}

/**
* A taint propagating data flow edge caused by the builtin array functions.
*/
private class ArrayFunctionTaintStep extends AdditionalTaintStep {
DataFlow::CallNode call;

ArrayFunctionTaintStep() {
this = call
}

override predicate step(DataFlow::Node pred, DataFlow::Node succ) {
// `array.map(function (elt, i, ary) { ... })`: if `array` is tainted, then so are
// `elt` and `ary`; similar for `forEach`
exists (string name, Function f, int i |
(name = "map" or name = "forEach") and
(i = 0 or i = 2) and
call.getArgument(0).analyze().getAValue().(AbstractFunction).getFunction() = f and
pred.(DataFlow::SourceNode).getAMethodCall(name) = call and
succ = DataFlow::parameterNode(f.getParameter(i))
)
or
// `array.map` with tainted return value in callback
exists (DataFlow::FunctionNode f |
call.(DataFlow::MethodCallNode).getMethodName() = "map" and
call.getArgument(0) = f and // Require the argument to be a closure to avoid spurious call/return flow
pred = f.getAReturn() and
succ = call
)
or
// `array.push(e)`, `array.unshift(e)`: if `e` is tainted, then so is `array`.
exists (string name |
name = "push" or
name = "unshift" |
pred = call.getAnArgument() and
succ.(DataFlow::SourceNode).getAMethodCall(name) = call
)
or
// `e = array.pop()`, `e = array.shift()`, or similar: if `array` is tainted, then so is `e`.
exists (string name |
name = "pop" or
name = "shift" or
name = "slice" or
name = "splice" |
call.(DataFlow::MethodCallNode).calls(pred, name) and
succ = call
)
or
// `e = Array.from(x)`: if `x` is tainted, then so is `e`.
call = DataFlow::globalVarRef("Array").getAPropertyRead("from").getACall() and
pred = call.getAnArgument() and
succ = call
}

}

/**
* A taint propagating data flow edge for assignments of the form `o[k] = v`, where
* `k` is not a constant and `o` refers to some object literal; in this case, we consider
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12 changes: 12 additions & 0 deletions javascript/ql/test/library-tests/TaintTracking/BasicTaintTracking.expected
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Expand Up @@ -3,3 +3,15 @@
| tst.js:2:13:2:20 | source() | tst.js:14:10:14:17 | x.sort() |
| tst.js:2:13:2:20 | source() | tst.js:17:10:17:10 | a |
| tst.js:2:13:2:20 | source() | tst.js:19:10:19:10 | a |
| tst.js:2:13:2:20 | source() | tst.js:23:10:23:10 | b |
| tst.js:2:13:2:20 | source() | tst.js:25:10:25:16 | x.pop() |
| tst.js:2:13:2:20 | source() | tst.js:26:10:26:18 | x.shift() |
| tst.js:2:13:2:20 | source() | tst.js:27:10:27:18 | x.slice() |
| tst.js:2:13:2:20 | source() | tst.js:28:10:28:19 | x.splice() |
| tst.js:2:13:2:20 | source() | tst.js:30:10:30:22 | Array.from(x) |
| tst.js:2:13:2:20 | source() | tst.js:33:14:33:16 | elt |
| tst.js:2:13:2:20 | source() | tst.js:35:14:35:16 | ary |
| tst.js:2:13:2:20 | source() | tst.js:39:14:39:16 | elt |
| tst.js:2:13:2:20 | source() | tst.js:41:14:41:16 | ary |
| tst.js:2:13:2:20 | source() | tst.js:44:10:44:30 | innocen ... ) => x) |
| tst.js:2:13:2:20 | source() | tst.js:45:10:45:24 | x.map(x2 => x2) |
26 changes: 26 additions & 0 deletions javascript/ql/test/library-tests/TaintTracking/tst.js
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Expand Up @@ -18,4 +18,30 @@ function test() {
a.push(x);
sink(a); // NOT OK

var b = [];
b.unshift(x);
sink(b); // NOT OK

sink(x.pop()); // NOT OK
sink(x.shift()); // NOT OK
sink(x.slice()); // NOT OK
sink(x.splice()); // NOT OK

sink(Array.from(x)); // NOT OK

x.map((elt, i, ary) => {
sink(elt); // NOT OK
sink(i); // OK
sink(ary); // NOT OK
});

x.forEach((elt, i, ary) => {
sink(elt); // NOT OK
sink(i); // OK
sink(ary); // NOT OK
});

sink(innocent.map(() => x)); // NOT OK
sink(x.map(x2 => x2)); // NOT OK

}