转于：猪猪谈安全 2023-03-31 22:00 发表于江苏
0x01 前言在Java中可用于执行系统命令常见的方式有两种，API为：java.lang.Runtime、java.lang.ProcessBuilder 0x02 java.lang.Runtime@GetMapping("/runtime/exec")
public String CommandExec(String cmd) {
Runtime run = Runtime.getRuntime(); //Runtime.getRuntime.exec
StringBuilder sb = new StringBuilder(); //ProcessBuilder.start()
try {
Process p = run.exec(cmd);
//只是调用了对应进程没有回显，需要从流中读取
BufferedInputStream in = new BufferedInputStream(p.getInputStream());
BufferedReader inBr = new BufferedReader(new InputStreamReader(in));
String tmpStr;
while ((tmpStr = inBr.readLine()) != null) {
sb.append(tmpStr);
}
if (p.waitFor() != 0) {
if (p.exitValue() == 1)
return "Command exec failed!!";
}
inBr.close();
in.close();
} catch (Exception e) {
return e.toString();
}
return sb.toString();
}最基础的Runtime.getRuntime().exec(cmd)，直接传入命令即可执行 0x03 java.lang.ProcessBuilder1. 直接传入参数导致命令执行 @GetMapping("/ProcessBuilder")
public String processBuilder(String cmd) {
StringBuilder sb = new StringBuilder();
try {
// String[] arrCmd = {"/bin/sh", "-c", cmd}; //linux
String[] arrCmd = {cmd}; //windows,windows下无需指定
ProcessBuilder processBuilder = new ProcessBuilder(arrCmd);
Process p = processBuilder.start();
BufferedInputStream in = new BufferedInputStream(p.getInputStream());
BufferedReader inBr = new BufferedReader(new InputStreamReader(in));
String tmpStr;
while ((tmpStr = inBr.readLine()) != null) {
sb.append(tmpStr);
}
} catch (Exception e) {
return e.toString();
}
return sb.toString();
}同样也是直接执行命令，不同的是使用的是ProcessBuilder来执行命令。ProcessBuilder传入参数为列表，第一个参数为可执行命令程序，后面的参数为执行的命令程序的参数 2. 传入参数拼接导致命令执行 @GetMapping("/codeinject")
public String codeInject(String filepath) throws IOException {
String[] cmdList = new String[]{"sh", "-c", "ls -la " + filepath};
//String[] cmdList = new String[]{"cmd.exe", "-c", "dir " + filepath};
ProcessBuilder builder = new ProcessBuilder(cmdList);
builder.redirectErrorStream(true);
Process process = builder.start();
return WebUtils.convertStreamToString(process.getInputStream());
}获取一个参数filepath，然后通过ProcessBuilder将数组cmdList中 的字符串拼接起来执行命令，由于没有对输入filepath进行过滤，原本用作查看目录下文件的一个功能就会被执行恶意命令。通过Java执行系统命令，与cmd中或者终端上一样执行shell命令，最典型的用法就是使用Runtime.getRuntime().exec(command)、new ProcessBuilder(cmdArray).start() 拼接后paylaod:http://localhost/codeinject?filepath=/tmp;%20id 3. Host头未过滤命令执行 @GetMapping("/codeinject/host")
public String codeInjectHost(HttpServletRequest request) throws IOException {
String host = request.getHeader("host");
logger.info(host);
String[] cmdList = new String[]{"sh", "-c", "curl " + host};
ProcessBuilder builder = new ProcessBuilder(cmdList);
builder.redirectErrorStream(true);
Process process = builder.start();
return WebUtils.convertStreamToString(process.getInputStream());
}代码中在header中的host中设置参数且未过滤拼接后传入ProcessBuilder导致命令执行 payload:Host: 192.168.1.4;id && pwd 修复方式： 利用SecurityUtil.cmdFilter来对传入的参数进行过滤，严格限制用户输入只能包含a-zA-Z0-9_-.字符 public static String cmdFilter(String input) {
if (!FILTER_PATTERN.matcher(input).matches()) {
return null;
}
return input;
}0x04 其它方式ScriptEngineManager @GetMapping("/jscmd")
public void jsEngine(String jsurl) throws Exception{
// js nashorn javascript ecmascript
ScriptEngine engine = new ScriptEngineManager().getEngineByName("js");
Bindings bindings = engine.getBindings(ScriptContext.ENGINE_SCOPE);//启动javascript引擎
String cmd = String.format("load(\"%s\")", jsurl);
engine.eval(cmd, bindings);
}yml @GetMapping("/vuln/yarm")
public void yarm(String content) {
Yaml y = new Yaml();
y.load(content);
}groovy @GetMapping("groovy")
public void groovyshell(String content) {
GroovyShell groovyShell = new GroovyShell();
groovyShell.evaluate(content);
}0x05 总结注意：java的Runtime.getRuntime.exec和ProcessBuilder.start，都是直接启动传入参数对应的进程,如果只是命令执行的部分参数可控，想在java中通过;、|、&等实现命令注入是行不通的， 例如这样传入id && whoami命令是无法执行的 存在问题的关键词： Runtime.getRuntime().exec()、new ProcessBuilder().start()、cmd
ScriptEngineManager、Yaml、GroovyShell
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发表于 2023-4-2 21:05:20
