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init: add PotentiallyUnguardedProtocolHandler query
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‎java/src/security/PotentiallyUnguardedProtocolHandler/PotentiallyUnguardedProtocolHandler.qhelp‎

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<!DOCTYPE qhelp SYSTEM "qhelp.dtd">
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<qhelp>
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<overview>
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<p>
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URL protocol handlers are used to handle any URL scheme supported by the native desktop.
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If URL inputs to these handlers are untrusted and not properly sanitized, they can be
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used to perform unintended actions by another application registered to handle the same
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protocol.
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</p>
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</overview>
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<recommendation>
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<p>
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Review protocol handler sinks and ensure that any URL inputs are properly sanitized if
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they come from untrusted sources.
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</p>
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</recommendation>
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<references>
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<li> Positive Security: <a
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href="https://positive.security/blog/url-open-rce">Allow
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arbitrary URLs, expect arbitrary code execution</a>
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</li>
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<li> CVE-2022-43550: <a href="https://hackerone.com/reports/1692603">Jitsi Desktop Client
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RCE By Interacting with Malicious URL Schemes on Windows</a>
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</li>
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</references>
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</qhelp>

‎java/src/security/PotentiallyUnguardedProtocolHandler/PotentiallyUnguardedProtocolHandler.ql‎

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/**
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* @name Potentially unguarded protocol handler invocation
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* @id tob/java/unguarded-protocol-handler
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* @description Detects calls to URL protocol handlers with untrusted input that may not be properly validated for dangerous protocols
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* @kind path-problem
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* @tags security
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* external/cwe/cwe-939
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* @precision medium
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* @problem.severity warning
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* @security-severity 6.5
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* @group security
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*/
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import java
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import semmle.code.java.dataflow.TaintTracking
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import semmle.code.java.dataflow.FlowSources
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import semmle.code.java.controlflow.Guards
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/**
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* A call to Desktop.browse() method for handling
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* TODO(alan): also support legacy/generic cases like invoking "rundll32 url.dll,FileProtocolHandler"
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*/
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class DesktopBrowseCall extends MethodCall {
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DesktopBrowseCall() {
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this.getMethod().hasName("browse") and
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this.getMethod().getDeclaringType().hasQualifiedName("java.awt", "Desktop")
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}
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Expr getUrlArgument() { result = this.getArgument(0) }
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string getDescription() { result = "Desktop.browse()" }
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}
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/**
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* A guard that checks the URL scheme/protocol signifying sanitization before launch
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*/
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predicate isUrlSchemeCheck(Guard g, Expr e, boolean branch) {
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exists(MethodCall mc |
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mc = g and
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e = mc.getQualifier*() and
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branch = true and
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(
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// getScheme() or getProtocol() check
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mc.getMethod().hasName(["equals", "equalsIgnoreCase", "startsWith", "matches"]) and
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exists(MethodCall getScheme |
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getScheme.getParent*() = mc and
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getScheme.getMethod().hasName(["getScheme", "getProtocol"])
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)
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or
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// URL string contains check like: url.contains("http://") or url.startsWith("https://")
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mc.getMethod().hasName(["contains", "startsWith", "matches", "indexOf"]) and
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exists(StringLiteral sl | sl = mc.getAnArgument() | sl.getValue().regexpMatch(".*://.*"))
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or
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// Pattern matching on the string representation
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mc.getMethod().hasName(["matches", "find"]) and
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mc.getQualifier().getType().(RefType).hasQualifiedName("java.util.regex", "Matcher")
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)
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)
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}
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/**
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* Configuration for tracking untrusted data to protocol handler invocations
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*/
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module PotentiallyUnguardedProtocolHandlerConfig implements DataFlow::ConfigSig {
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predicate isSource(DataFlow::Node source) { source instanceof RemoteFlowSource }
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predicate isSink(DataFlow::Node sink) {
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exists(DesktopBrowseCall call | sink.asExpr() = call.getUrlArgument())
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}
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predicate isBarrier(DataFlow::Node node) {
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// Consider sanitized if there's a guard checking the scheme
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node = DataFlow::BarrierGuard<isUrlSchemeCheck/3>::getABarrierNode()
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}
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}
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module PotentiallyUnguardedProtocolHandlerFlow =
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TaintTracking::Global<PotentiallyUnguardedProtocolHandlerConfig>;
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import PotentiallyUnguardedProtocolHandlerFlow::PathGraph
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from
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PotentiallyUnguardedProtocolHandlerFlow::PathNode source,
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PotentiallyUnguardedProtocolHandlerFlow::PathNode sink, DesktopBrowseCall call
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where
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PotentiallyUnguardedProtocolHandlerFlow::flowPath(source, sink) and
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sink.getNode().asExpr() = call.getUrlArgument()
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select call, source, sink,
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call.getDescription() +
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" is called with untrusted input from $@ without proper URL scheme validation.",
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source.getNode(), "this source"

‎java/test/query-tests/security/PotentiallyUnguardedProtocolHandler/PotentiallyUnguardedProtocolHandler.expected‎

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edges
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| PotentiallyUnguardedProtocolHandler.java:10:22:10:48 | getParameter(...) : String | PotentiallyUnguardedProtocolHandler.java:11:45:11:47 | url : String | provenance | Src:MaD:46190 |
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| PotentiallyUnguardedProtocolHandler.java:11:45:11:47 | url : String | PotentiallyUnguardedProtocolHandler.java:11:37:11:48 | new URI(...) | provenance | MaD:44428 Sink:MaD:43969 |
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| PotentiallyUnguardedProtocolHandler.java:20:22:20:48 | getParameter(...) : String | PotentiallyUnguardedProtocolHandler.java:21:27:21:29 | url : String | provenance | Src:MaD:46190 |
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| PotentiallyUnguardedProtocolHandler.java:21:19:21:30 | new URI(...) : URI | PotentiallyUnguardedProtocolHandler.java:23:41:23:43 | uri | provenance | Sink:MaD:43969 |
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| PotentiallyUnguardedProtocolHandler.java:21:27:21:29 | url : String | PotentiallyUnguardedProtocolHandler.java:21:19:21:30 | new URI(...) : URI | provenance | MaD:44428 |
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| PotentiallyUnguardedProtocolHandler.java:34:22:34:48 | getParameter(...) : String | PotentiallyUnguardedProtocolHandler.java:35:27:35:29 | url : String | provenance | Src:MaD:46190 |
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| PotentiallyUnguardedProtocolHandler.java:35:19:35:30 | new URI(...) : URI | PotentiallyUnguardedProtocolHandler.java:39:41:39:43 | uri | provenance | Sink:MaD:43969 |
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| PotentiallyUnguardedProtocolHandler.java:35:27:35:29 | url : String | PotentiallyUnguardedProtocolHandler.java:35:19:35:30 | new URI(...) : URI | provenance | MaD:44428 |
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nodes
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| PotentiallyUnguardedProtocolHandler.java:10:22:10:48 | getParameter(...) : String | semmle.label | getParameter(...) : String |
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| PotentiallyUnguardedProtocolHandler.java:11:37:11:48 | new URI(...) | semmle.label | new URI(...) |
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| PotentiallyUnguardedProtocolHandler.java:11:45:11:47 | url : String | semmle.label | url : String |
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| PotentiallyUnguardedProtocolHandler.java:20:22:20:48 | getParameter(...) : String | semmle.label | getParameter(...) : String |
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| PotentiallyUnguardedProtocolHandler.java:21:19:21:30 | new URI(...) : URI | semmle.label | new URI(...) : URI |
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| PotentiallyUnguardedProtocolHandler.java:21:27:21:29 | url : String | semmle.label | url : String |
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| PotentiallyUnguardedProtocolHandler.java:23:41:23:43 | uri | semmle.label | uri |
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| PotentiallyUnguardedProtocolHandler.java:34:22:34:48 | getParameter(...) : String | semmle.label | getParameter(...) : String |
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| PotentiallyUnguardedProtocolHandler.java:35:19:35:30 | new URI(...) : URI | semmle.label | new URI(...) : URI |
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| PotentiallyUnguardedProtocolHandler.java:35:27:35:29 | url : String | semmle.label | url : String |
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| PotentiallyUnguardedProtocolHandler.java:39:41:39:43 | uri | semmle.label | uri |
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subpaths
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#select
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| PotentiallyUnguardedProtocolHandler.java:11:9:11:49 | browse(...) | PotentiallyUnguardedProtocolHandler.java:10:22:10:48 | getParameter(...) : String | PotentiallyUnguardedProtocolHandler.java:11:37:11:48 | new URI(...) | Desktop.browse() is called with untrusted input from $@ without proper URL scheme validation. | PotentiallyUnguardedProtocolHandler.java:10:22:10:48 | getParameter(...) | this source |
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| PotentiallyUnguardedProtocolHandler.java:23:13:23:44 | browse(...) | PotentiallyUnguardedProtocolHandler.java:20:22:20:48 | getParameter(...) : String | PotentiallyUnguardedProtocolHandler.java:23:41:23:43 | uri | Desktop.browse() is called with untrusted input from $@ without proper URL scheme validation. | PotentiallyUnguardedProtocolHandler.java:20:22:20:48 | getParameter(...) | this source |
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| PotentiallyUnguardedProtocolHandler.java:39:13:39:44 | browse(...) | PotentiallyUnguardedProtocolHandler.java:34:22:34:48 | getParameter(...) : String | PotentiallyUnguardedProtocolHandler.java:39:41:39:43 | uri | Desktop.browse() is called with untrusted input from $@ without proper URL scheme validation. | PotentiallyUnguardedProtocolHandler.java:34:22:34:48 | getParameter(...) | this source |

‎java/test/query-tests/security/PotentiallyUnguardedProtocolHandler/PotentiallyUnguardedProtocolHandler.java‎

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import java.awt.Desktop;
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import java.io.IOException;
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import java.net.URI;
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import java.net.URISyntaxException;
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import javax.servlet.http.HttpServletRequest;
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public class PotentiallyUnguardedProtocolHandler {
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public void bad1(HttpServletRequest request) throws IOException, URISyntaxException {
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String url = request.getParameter("url");
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Desktop.getDesktop().browse(new URI(url));
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}
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public void bad2(String userInput) throws IOException, URISyntaxException {
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URI uri = new URI(userInput);
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Desktop.getDesktop().browse(uri);
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}
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public void safe1(HttpServletRequest request) throws IOException, URISyntaxException {
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String url = request.getParameter("url");
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URI uri = new URI(url);
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if (uri.getScheme().equals("https") || uri.getScheme().equals("http")) {
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Desktop.getDesktop().browse(uri);
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}
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}
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public void safe2(String userInput) throws IOException, URISyntaxException {
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if (userInput.startsWith("https://") || userInput.startsWith("http://")) {
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Desktop.getDesktop().browse(new URI(userInput));
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}
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}
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public void bad3(HttpServletRequest request) throws IOException, URISyntaxException {
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String url = request.getParameter("url");
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URI uri = new URI(url);
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// Weak check - only checks if scheme exists, not what it is
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if (uri.getScheme() != null) {
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Desktop.getDesktop().browse(uri);
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}
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}
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public void safe3(String userInput) throws IOException, URISyntaxException {
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URI uri = new URI(userInput);
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String scheme = uri.getScheme();
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if (scheme != null && (scheme.equalsIgnoreCase("http") || scheme.equalsIgnoreCase("https"))) {
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Desktop.getDesktop().browse(uri);
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}
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}
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public void safe4() throws IOException, URISyntaxException {
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// hardcoded, no untrusted input
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Desktop.getDesktop().browse(new URI("https://example.com"));
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}
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}

‎java/test/query-tests/security/PotentiallyUnguardedProtocolHandler/PotentiallyUnguardedProtocolHandler.qlref‎

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security/PotentiallyUnguardedProtocolhandler/PotentiallyUnguardedProtocolhandler.ql

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