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JS: Add result.download to Express as Path Traversal Sink #18749

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Merged
asgerf merged 3 commits into from
Feb 19, 2025
Merged

JS: Add result.download to Express as Path Traversal Sink #18749

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d0ed0fd
Add download to Express
Kwstubbs Feb 12, 2025
f5521ca
Formatting
Kwstubbs Feb 12, 2025
253882c
Update javascript/ql/lib/change-notes/2025-02-12-express-download.md
Kwstubbs Feb 12, 2025
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4 changes: 4 additions & 0 deletions javascript/ql/lib/change-notes/2025-02-12-express-download.md
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@@ -0,0 +1,4 @@
---
category: minorAnalysis
---
* The `response.download()` function in `express` is now recognized as a sink for path traversal attacks.
17 changes: 17 additions & 0 deletions javascript/ql/lib/semmle/javascript/frameworks/Express.qll
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Expand Up @@ -960,6 +960,23 @@ module Express {
}
}

/** A call to `response.download`, considered as a file system access. */
private class ResponseDownloadAsFileSystemAccess extends FileSystemReadAccess,
DataFlow::MethodCallNode
{
ResponseDownloadAsFileSystemAccess() {
exists(string name | name = "download" | this.calls(any(ResponseNode res), name))
}

override DataFlow::Node getADataNode() { none() }

override DataFlow::Node getAPathArgument() { result = this.getArgument(0) }

override DataFlow::Node getRootPathArgument() {
result = this.(DataFlow::CallNode).getOptionArgument([1, 2], "root")
}
}

/**
* A function that flows to a route setup.
*/
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12 changes: 12 additions & 0 deletions javascript/ql/test/query-tests/Security/CWE-022/TaintedPath/TaintedPath.expected
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Expand Up @@ -450,6 +450,12 @@ nodes
| tainted-sendFile.js:24:37:24:48 | req.params.x | semmle.label | req.params.x |
| tainted-sendFile.js:25:16:25:46 | path.jo ... rams.x) | semmle.label | path.jo ... rams.x) |
| tainted-sendFile.js:25:34:25:45 | req.params.x | semmle.label | req.params.x |
| tainted-sendFile.js:30:16:30:33 | req.param("gimme") | semmle.label | req.param("gimme") |
| tainted-sendFile.js:33:16:33:48 | homeDir ... arams.x | semmle.label | homeDir ... arams.x |
| tainted-sendFile.js:33:37:33:48 | req.params.x | semmle.label | req.params.x |
| tainted-sendFile.js:35:16:35:46 | path.jo ... rams.x) | semmle.label | path.jo ... rams.x) |
| tainted-sendFile.js:35:34:35:45 | req.params.x | semmle.label | req.params.x |
| tainted-sendFile.js:38:43:38:58 | req.param("dir") | semmle.label | req.param("dir") |
| tainted-string-steps.js:6:7:6:48 | path | semmle.label | path |
| tainted-string-steps.js:6:14:6:37 | url.par ... , true) | semmle.label | url.par ... , true) |
| tainted-string-steps.js:6:14:6:43 | url.par ... ).query | semmle.label | url.par ... ).query |
Expand Down Expand Up @@ -895,6 +901,8 @@ edges
| tainted-promise-steps.js:12:20:12:23 | path | tainted-promise-steps.js:12:44:12:47 | path | provenance | |
| tainted-sendFile.js:24:37:24:48 | req.params.x | tainted-sendFile.js:24:16:24:49 | path.re ... rams.x) | provenance | Config |
| tainted-sendFile.js:25:34:25:45 | req.params.x | tainted-sendFile.js:25:16:25:46 | path.jo ... rams.x) | provenance | Config |
| tainted-sendFile.js:33:37:33:48 | req.params.x | tainted-sendFile.js:33:16:33:48 | homeDir ... arams.x | provenance | Config |
| tainted-sendFile.js:35:34:35:45 | req.params.x | tainted-sendFile.js:35:16:35:46 | path.jo ... rams.x) | provenance | Config |
| tainted-string-steps.js:6:7:6:48 | path | tainted-string-steps.js:8:18:8:21 | path | provenance | |
| tainted-string-steps.js:6:7:6:48 | path | tainted-string-steps.js:9:18:9:21 | path | provenance | |
| tainted-string-steps.js:6:7:6:48 | path | tainted-string-steps.js:10:18:10:21 | path | provenance | |
Expand Down Expand Up @@ -1114,6 +1122,10 @@ subpaths
| tainted-sendFile.js:18:43:18:58 | req.param("dir") | tainted-sendFile.js:18:43:18:58 | req.param("dir") | tainted-sendFile.js:18:43:18:58 | req.param("dir") | This path depends on a $@. | tainted-sendFile.js:18:43:18:58 | req.param("dir") | user-provided value |
| tainted-sendFile.js:24:16:24:49 | path.re ... rams.x) | tainted-sendFile.js:24:37:24:48 | req.params.x | tainted-sendFile.js:24:16:24:49 | path.re ... rams.x) | This path depends on a $@. | tainted-sendFile.js:24:37:24:48 | req.params.x | user-provided value |
| tainted-sendFile.js:25:16:25:46 | path.jo ... rams.x) | tainted-sendFile.js:25:34:25:45 | req.params.x | tainted-sendFile.js:25:16:25:46 | path.jo ... rams.x) | This path depends on a $@. | tainted-sendFile.js:25:34:25:45 | req.params.x | user-provided value |
| tainted-sendFile.js:30:16:30:33 | req.param("gimme") | tainted-sendFile.js:30:16:30:33 | req.param("gimme") | tainted-sendFile.js:30:16:30:33 | req.param("gimme") | This path depends on a $@. | tainted-sendFile.js:30:16:30:33 | req.param("gimme") | user-provided value |
| tainted-sendFile.js:33:16:33:48 | homeDir ... arams.x | tainted-sendFile.js:33:37:33:48 | req.params.x | tainted-sendFile.js:33:16:33:48 | homeDir ... arams.x | This path depends on a $@. | tainted-sendFile.js:33:37:33:48 | req.params.x | user-provided value |
| tainted-sendFile.js:35:16:35:46 | path.jo ... rams.x) | tainted-sendFile.js:35:34:35:45 | req.params.x | tainted-sendFile.js:35:16:35:46 | path.jo ... rams.x) | This path depends on a $@. | tainted-sendFile.js:35:34:35:45 | req.params.x | user-provided value |
| tainted-sendFile.js:38:43:38:58 | req.param("dir") | tainted-sendFile.js:38:43:38:58 | req.param("dir") | tainted-sendFile.js:38:43:38:58 | req.param("dir") | This path depends on a $@. | tainted-sendFile.js:38:43:38:58 | req.param("dir") | user-provided value |
| tainted-string-steps.js:8:18:8:34 | path.substring(4) | tainted-string-steps.js:6:24:6:30 | req.url | tainted-string-steps.js:8:18:8:34 | path.substring(4) | This path depends on a $@. | tainted-string-steps.js:6:24:6:30 | req.url | user-provided value |
| tainted-string-steps.js:9:18:9:37 | path.substring(0, i) | tainted-string-steps.js:6:24:6:30 | req.url | tainted-string-steps.js:9:18:9:37 | path.substring(0, i) | This path depends on a $@. | tainted-string-steps.js:6:24:6:30 | req.url | user-provided value |
| tainted-string-steps.js:10:18:10:31 | path.substr(4) | tainted-string-steps.js:6:24:6:30 | req.url | tainted-string-steps.js:10:18:10:31 | path.substr(4) | This path depends on a $@. | tainted-string-steps.js:6:24:6:30 | req.url | user-provided value |
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14 changes: 14 additions & 0 deletions javascript/ql/test/query-tests/Security/CWE-022/TaintedPath/tainted-sendFile.js
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Expand Up @@ -25,4 +25,18 @@ app.get('/some/path/:x', function(req, res) {
res.sendfile(path.join('data', req.params.x)); // NOT OK

res.sendFile(homeDir + path.join('data', req.params.x)); // kinda OK - can only escape from 'data/'

// BAD: downloading a file based on un-sanitized query parameters
res.download(req.param("gimme"));

// BAD: download allows ../
res.download(homeDir + '/data/' + req.params.x);

res.download(path.join('data', req.params.x)); // NOT OK

// BAD: doesn't help if user controls root
res.download(req.param("file"), { root: req.param("dir") });

// GOOD: ensures files cannot be accessed outside of root folder
res.download(req.param("gimme"), { root: process.cwd() });
});