WSO2 RCE（CVE-2022-29464）漏洞利用与分析文章。
CVE-2022-29464 是WSO2中的严重漏洞，由 Orange Tsai 发现。该漏洞是未经身份验证的无限制任意文件上传，允许未经身份验证的攻击者通过上传恶意JSP文件在WSO2服务器上获得RCE。
存在漏洞的上传路径为 /fileupload，由 FileUploadServlet servlet 处理。并且从 identity.xml 配置文件中可以看出，该路径未受IAM保护：```xml
并且同样不受默认登录措施的保护，`handleSecurity()` 是负责保护WSO2所服务的不同路由的函数，并提供了一种对接收到的HTTP请求执行安全检查的机制。`handleSecurity()` 将调用 `CarbonUILoginUtil.handleLoginPageRequest()`，并根据其返回值决定允许或拒绝对所请求URI的访问：```java
public boolean handleSecurity(HttpServletRequest request, HttpServletResponse response)
throws IOException {
[snipped]
if ((val = CarbonUILoginUtil.handleLoginPageRequest(requestedURI, request, response,
authenticated, context, indexPageURL)) != CarbonUILoginUtil.CONTINUE) {
if (val == CarbonUILoginUtil.RETURN_TRUE) {
return true;
} else {
return false;
}
}
[snipped]
}
当路径为 /fileupload 时，CarbonUILoginUtil.handleLoginPageRequest() 返回 CarbonUILoginUtil.RETURN_TRUE：```java
protected static int handleLoginPageRequest(String requestedURI, HttpServletRequest request,
HttpServletResponse response, boolean authenticated, String context, String indexPageURL)
throws IOException {
boolean isTryIt = requestedURI.indexOf("admin/jsp/WSRequestXSSproxy_ajaxprocessor.jsp") > -1;
boolean isFileDownload = requestedURI.endsWith("/filedownload");
if ((requestedURI.indexOf("login.jsp") > -1
|| requestedURI.indexOf("login_ajaxprocessor.jsp") > -1
|| requestedURI.indexOf("admin/layout/template.jsp") > -1
|| isFileDownload
|| requestedURI.endsWith("/fileupload")
|| requestedURI.indexOf("/fileupload/") > -1
|| requestedURI.indexOf("login_action.jsp") > -1
|| isTryIt
|| requestedURI.indexOf("tryit/JAXRSRequestXSSproxy_ajaxprocessor.jsp") > -1)
&& !requestedURI.contains(";")) {
if ((requestedURI.indexOf("login.jsp") > -1
|| requestedURI.indexOf("login_ajaxprocessor.jsp") > -1 || requestedURI
.indexOf("login_action.jsp") > -1) && authenticated) {
[snipped]
} else if ((isTryIt || isFileDownload) && !authenticated) {
[snipped]
} else if (requestedURI.indexOf("login_action.jsp") > -1 && !authenticated) {
[snipped]
} else {
if (log.isDebugEnabled()) {
log.debug("Skipping security checks for " + requestedURI);
}
return RETURN_TRUE;
}
}
return CONTINUE;
}
当 `CarbonUILoginUtil.handleLoginPageRequest()` 返回 `CarbonUILoginUtil.RETURN_TRUE` 时，`handleSecurity()` 将返回 `true`，从而无需认证即可访问 `/fileupload`。
`FileUploadServlet` 这个 servlet 在 [`init()`](https://github.com/wso2/carbon-kernel/blob/d47232dfb2b26c0ef18a74e2ef4aa503caa59697/core/org.wso2.carbon.ui/src/main/java/org/wso2/carbon/ui/transports/FileUploadServlet.java#L71) 方法中，通过一系列方法调用，最终从 `carbon.xml` 配置文件加载多个上传文件格式/操作以及处理每种格式的对象。```java
public void init(ServletConfig servletConfig) throws ServletException {
this.servletConfig = servletConfig;
try {
fileUploadExecutorManager = new FileUploadExecutorManager(bundleContext, configContext, webContext);
//Registering FileUploadExecutor Manager as an OSGi service
bundleContext.registerService(FileUploadExecutorManager.class.getName(), fileUploadExecutorManager, null);
} catch (CarbonException e) {
log.error("Exception occurred while trying to initialize FileUploadServlet", e);
throw new ServletException(e);
}
}
FileUploadExecutorManager类的构造函数如下：```java
public FileUploadExecutorManager(BundleContext bundleContext,
ConfigurationContext configCtx,
String webContext) throws CarbonException {
this.bundleContext = bundleContext;
this.configContext = configCtx;
this.webContext = webContext;
this.loadExecutorMap();
}
构造函数调用私有方法 [`loadExecutorMap()`](https://github.com/wso2/carbon-kernel/blob/d47232dfb2b26c0ef18a74e2ef4aa503caa59697/core/org.wso2.carbon.ui/src/main/java/org/wso2/carbon/ui/transports/fileupload/FileUploadExecutorManager.java#L131)，该方法负责加载配置：```java
private void loadExecutorMap() throws CarbonException {
[snipped]
try {
documentElement = XMLUtils.toOM(serverConfiguration.getDocumentElement());
} catch (Exception e) {
String msg = "Unable to read Server Configuration.";
log.error(msg);
throw new CarbonException(msg, e);
}
[snipped]
OMElement fileUploadConfigElement =
documentElement.getFirstChildWithName(
new QName(ServerConstants.CARBON_SERVER_XML_NAMESPACE, "FileUploadConfig"));
for (Iterator iterator = fileUploadConfigElement.getChildElements(); iterator.hasNext();) {
OMElement mapppingElement = (OMElement) iterator.next();
if (mapppingElement.getLocalName().equalsIgnoreCase("Mapping")) {
OMElement actionsElement =
mapppingElement.getFirstChildWithName(
new QName(ServerConstants.CARBON_SERVER_XML_NAMESPACE, "Actions"));
String confPath = System.getProperty(CarbonBaseConstants.CARBON_CONFIG_DIR_PATH);
[snipped]
文件上传格式配置位于XML配置文件中的FileUploadConfig命名空间内，这是默认配置：```xml
100
<Mapping>
<Actions>
<Action>keystore</Action>
<Action>certificate</Action>
<Action>*</Action>
</Actions>
<Class>org.wso2.carbon.ui.transports.fileupload.AnyFileUploadExecutor</Class>
</Mapping>
<Mapping>
<Actions>
<Action>jarZip</Action>
</Actions>
<Class>org.wso2.carbon.ui.transports.fileupload.JarZipUploadExecutor</Class>
</Mapping>
<Mapping>
<Actions>
<Action>dbs</Action>
</Actions>
<Class>org.wso2.carbon.ui.transports.fileupload.DBSFileUploadExecutor</Class>
</Mapping>
<Mapping>
<Actions>
<Action>tools</Action>
</Actions>
<Class>org.wso2.carbon.ui.transports.fileupload.ToolsFileUploadExecutor</Class>
</Mapping>
<Mapping>
<Actions>
<Action>toolsAny</Action>
</Actions>
<Class>org.wso2.carbon.ui.transports.fileupload.ToolsAnyFileUploadExecutor</Class>
</Mapping>
</FileUploadConfig>
`loadExecutorMap()` 方法会创建并填充一个 `<Action, Class>` 类型的 `HashMap`，其中包含从配置文件中提取的 Actions 和 Classes。该映射将在后续用于选择适当的类来处理特定格式/动作。
之后，当 `/fileupload` 路由收到 POST 请求时，会调用 Servlet 的 [`doPost()`](https://github.com/wso2/carbon-kernel/blob/d47232dfb2b26c0ef18a74e2ef4aa503caa59697/core/org.wso2.carbon.ui/src/main/java/org/wso2/carbon/ui/transports/FileUploadServlet.java#L53) 方法。该方法仅将请求和响应对象转发给 `fileUploadExecutorManager` 的 `execute()` 方法，而 `fileUploadExecutorManager` 是在 `init()` 中初始化的。```java
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
try {
fileUploadExecutorManager.execute(request, response);
} catch (Exception e) {
String msg = "File upload failed ";
log.error(msg, e);
throw new ServletException(e);
}
}
execute() 方法在请求 URL 中 fileupload/ 字符串之后进行分割，这意味着它提取请求 URL 中 /fileupload/ 之后的部分，并将其赋值给 actionString。```java
public boolean execute(HttpServletRequest request,
HttpServletResponse response) throws IOException {
HttpSession session = request.getSession();
String cookie = (String) session.getAttribute(ServerConstants.ADMIN_SERVICE_COOKIE);
request.setAttribute(CarbonConstants.ADMIN_SERVICE_COOKIE, cookie);
request.setAttribute(CarbonConstants.WEB_CONTEXT, webContext);
request.setAttribute(CarbonConstants.SERVER_URL,
CarbonUIUtil.getServerURL(request.getSession().getServletContext(),
request.getSession()));
String requestURI = request.getRequestURI();
//TODO - fileupload is hardcoded
int indexToSplit = requestURI.indexOf("fileupload/") + "fileupload/".length();
String actionString = requestURI.substring(indexToSplit);
// Register execution handlers
FileUploadExecutionHandlerManager execHandlerManager =
new FileUploadExecutionHandlerManager();
CarbonXmlFileUploadExecHandler carbonXmlExecHandler =
new CarbonXmlFileUploadExecHandler(request, response, actionString);
execHandlerManager.addExecHandler(carbonXmlExecHandler);
OSGiFileUploadExecHandler osgiExecHandler =
new OSGiFileUploadExecHandler(request, response);
execHandlerManager.addExecHandler(osgiExecHandler);
AnyFileUploadExecHandler anyFileExecHandler =
new AnyFileUploadExecHandler(request, response);
execHandlerManager.addExecHandler(anyFileExecHandler);
execHandlerManager.startExec();
return true;
}
`actionString` 被传递给 `CarbonXmlFileUploadExecHandler` 类的构造函数，同时传入 `request` 和 `response`：```java
private CarbonXmlFileUploadExecHandler(HttpServletRequest request,
HttpServletResponse response,
String actionString) {
this.request = request;
this.response = response;
this.actionString = actionString;
}
构造函数会将它们保存到其属性中。
之后，carbonXmlExecHandler 对象和其他对象将通过 addExecHandler() 方法添加到 execHandlerManager。```java
public void addExecHandler(FileUploadExecutionHandler handler) {
if (prevHandler != null) {
prevHandler.setNext(handler);
} else {
firstHandler = handler;
}
prevHandler = handler;
}
然后调用 `execHandlerManager.startExec()`：```java
public void startExec() throws IOException {
firstHandler.execute();
}
startExec() 调用第一个添加的对象（即 CarbonXmlFileUploadExecHandler）的 execute() 方法：```java
public void execute() throws IOException {
boolean foundExecutor = false;
for (String key : executorMap.keySet()) {
if (key.equals(actionString)) {
AbstractFileUploadExecutor obj = executorMap.get(key);
foundExecutor = true;
obj.executeGeneric(request, response, configContext);
break;
}
}
if (!foundExecutor) {
next();
}
}
[`execute()`](https://github.com/wso2/carbon-kernel/blob/d47232dfb2b26c0ef18a74e2ef4aa503caa59697/core/org.wso2.carbon.ui/src/main/java/org/wso2/carbon/ui/transports/fileupload/FileUploadExecutorManager.java#L430) 遍历先前创建的 `<Action, Class>` 的 `HashMap`，找到与 `actionString` 相等的 Action（键），如果找到，则调用与该 Action 关联的对象的 `executeGeneric()` 方法。
回顾一下，默认配置有 7 个动作，分别是：
* `keystore`、`certificate`、`*` 由 `org.wso2.carbon.ui.transports.fileupload.AnyFileUploadExecutor` 处理
* `jarZip` 由 `org.wso2.carbon.ui.transports.fileupload.JarZipUploadExecutor` 处理
* `dbs` 由 `org.wso2.carbon.ui.transports.fileupload.DBSFileUploadExecutor` 处理
* `tools` 由 `org.wso2.carbon.ui.transports.fileupload.ToolsFileUploadExecutor` 处理
* `toolsAny` 由 `org.wso2.carbon.ui.transports.fileupload.ToolsAnyFileUploadExecutor` 处理
每个对象处理上传的方式不同，有些接受特定扩展名。
我发现存在任意文件写入漏洞的第一个对象是 `toolsAny`（[`ToolsAnyFileUploadExecutor`](https://github.com/wso2/carbon-kernel/blob/4.4.x/core/org.wso2.carbon.ui/src/main/java/org/wso2/carbon/ui/transports/fileupload/ToolsAnyFileUploadExecutor.java)）。
`ToolsAnyFileUploadExecutor` 没有 `executeGeneric()` 方法，但它继承了 [`AbstractFileUploadExecutor`](https://github.com/wso2/carbon-kernel/blob/d47232dfb2b26c0ef18a74e2ef4aa503caa59697/core/org.wso2.carbon.ui/src/main/java/org/wso2/carbon/ui/transports/fileupload/AbstractFileUploadExecutor.java#L61)，而该类确实有一个 [`executeGeneric()`](https://github.com/wso2/carbon-kernel/blob/d47232dfb2b26c0ef18a74e2ef4aa503caa59697/core/org.wso2.carbon.ui/src/main/java/org/wso2/carbon/ui/transports/fileupload/AbstractFileUploadExecutor.java#L97) 方法：```java
boolean executeGeneric(HttpServletRequest request,
HttpServletResponse response,
ConfigurationContext configurationContext) throws IOException {//,
// CarbonException {
this.configurationContext = configurationContext;
try {
parseRequest(request);
return execute(request, response);
} catch (FileUploadFailedException e) {
sendErrorRedirect(request, response, e);
} catch (FileSizeLimitExceededException e) {
sendErrorRedirect(request, response, e);
} catch (CarbonException e) {
sendErrorRedirect(request, response, e);
}
return false;
}
executeGeneric() 首先调用 parseRequest()，并将请求对象作为参数传入。```java
protected void parseRequest(HttpServletRequest request) throws FileUploadFailedException,
FileSizeLimitExceededException {
fileItemsMap.set(new HashMap<String, ArrayList>());
formFieldsMap.set(new HashMap<String, ArrayList>());
ServletRequestContext servletRequestContext = new ServletRequestContext(request);
boolean isMultipart = ServletFileUpload.isMultipartContent(servletRequestContext);
Long totalFileSize = 0L;
if (isMultipart) {
List items;
try {
items = parseRequest(servletRequestContext);
} catch (FileUploadException e) {
String msg = "File upload failed";
log.error(msg, e);
throw new FileUploadFailedException(msg, e);
}
boolean multiItems = false;
if (items.size() > 1) {
multiItems = true;
}
// Add the uploaded items to the corresponding maps.
for (Iterator iter = items.iterator(); iter.hasNext();) {
FileItem item = (FileItem) iter.next();
String fieldName = item.getFieldName().trim();
if (item.isFormField()) {
if (formFieldsMap.get().get(fieldName) == null) {
formFieldsMap.get().put(fieldName, new ArrayList<String>());
}
try {
formFieldsMap.get().get(fieldName).add(new String(item.get(), "UTF-8"));
} catch (UnsupportedEncodingException ignore) {
}
} else {
String fileName = item.getName();
if ((fileName == null || fileName.length() == 0) && multiItems) {
continue;
}
if (fileItemsMap.get().get(fieldName) == null) {
fileItemsMap.get().put(fieldName, new ArrayList<FileItemData>());
}
totalFileSize += item.getSize();
if (totalFileSize < totalFileUploadSizeLimit) {
fileItemsMap.get().get(fieldName).add(new FileItemData(item));
} else {
throw new FileSizeLimitExceededException(getFileSizeLimit() / 1024 / 1024);
}
}
}
}
}
它首先确保POST请求是一个多部分POST请求，然后提取上传的文件，确保POST请求至少包含一个上传文件，并验证其是否超过最大文件大小。
在从`parseRequest()`返回后，`executeGeneric()`现在将调用`execute()`方法，该方法被`ToolsAnyFileUploadExecutor`[覆盖](https://github.com/wso2/carbon-kernel/blob/d47232dfb2b26c0ef18a74e2ef4aa503caa59697/core/org.wso2.carbon.ui/src/main/java/org/wso2/carbon/ui/transports/fileupload/ToolsAnyFileUploadExecutor.java#L36)：```java
@Override
public boolean execute(HttpServletRequest request,
HttpServletResponse response) throws CarbonException, IOException {
PrintWriter out = response.getWriter();
try {
Map fileResourceMap =
(Map) configurationContext
.getProperty(ServerConstants.FILE_RESOURCE_MAP);
if (fileResourceMap == null) {
fileResourceMap = new TreeBidiMap();
configurationContext.setProperty(ServerConstants.FILE_RESOURCE_MAP,
fileResourceMap);
}
List<FileItemData> fileItems = getAllFileItems();
//String filePaths = "";
for (FileItemData fileItem : fileItems) {
String uuid = String.valueOf(
System.currentTimeMillis() + Math.random());
String serviceUploadDir =
configurationContext
.getProperty(ServerConstants.WORK_DIR) +
File.separator +
"extra" + File
.separator +
uuid + File.separator;
File dir = new File(serviceUploadDir);
if (!dir.exists()) {
dir.mkdirs();
}
File uploadedFile = new File(dir, fileItem.getFileItem().getFieldName());
try (FileOutputStream fileOutStream = new FileOutputStream(uploadedFile)) {
fileItem.getDataHandler().writeTo(fileOutStream);
fileOutStream.flush();
}
response.setContentType("text/plain; charset=utf-8");
//filePaths = filePaths + uploadedFile.getAbsolutePath() + ",";
fileResourceMap.put(uuid, uploadedFile.getAbsolutePath());
out.write(uuid);
}
//filePaths = filePaths.substring(0, filePaths.length() - 1);
//out.write(filePaths);
out.flush();
} catch (Exception e) {
log.error("File upload FAILED", e);
out.write("<script type=\"text/javascript\">" +
"top.wso2.wsf.Util.alertWarning('File upload FAILED. File may be non-existent or invalid.');" +
"</script>");
} finally {
out.close();
}
return true;
}
这里正是漏洞所在：execute() 方法存在路径遍历漏洞，因为它信任 POST 请求中用户提供的文件名。如果不进行路径遍历转义，文件实际上会被保存到临时目录之外：```
./tmp/work/extra/$uuid/$filename
响应中返回了 `uuid`：
文件可以在以下位置找到：
现在我们需要逃逸出 `tmp` 目录，并将我们的 JSP shell 添加到 WSO2 提供服务的某个位置。
让我们找到 tomcat 的 `appBase` 目录：
该目录是部署在 tomcat 上的应用程序的位置，其中包含多个已部署的 WAR 应用程序以及它们的原始 WAR 文件：```
./repository/deployment/server/webapps
其中一个应用程序是 authenticationendpoint（//host/authenticationendpoint），它处理对 WSO2 的认证，其位置为：```
./repository/deployment/server/webapps/authenticationendpoint
**注意：** 我们也可以利用该漏洞在 `appBase` 目录下创建自己的新目录（上下文路径），并且该目录会被自动部署，但我只使用一个并继续使用 `authenticationendpoint`。
# PoC
* 使用 Burpsuite：
* 使用 exploiy.py：
> 用法：
> ```
> python3 exploit.py https://host:9443/ ArbitraryShellName.jsp
> ```
