CRAXweb: Web Testing and Attacks through QEMU in S2E. Shih-Kun Huang National Chiao Tung University Hsinchu, Taiwan

Transcription

1 CRAXweb: Web Testing and Attacks through QEMU in S2E Shih-Kun Huang National Chiao Tung University Hsinchu, Taiwan

2 Motivation Symbolic Execution is effective to crash applications Catchconv, Bitfuzz, Taintscope, and Ardilla (PHP) Should be effective for Web Testing Symbolic Execution can also automate exploit generation process AEG, MAYHEM, CRAX Should be feasible to automate Web Attack (exploit) generation

3 How Effective of Automatic Exploit Generation for non-web applications Mplayer (1.5MLOC) (CVE ) MPlayer 1.0rc2 and SVN before r seconds Microsoft Office Word (CVE ) Microsoft Office < seconds Nginx (CVE ) nginx 1.3.9/1.4.0 stack buffer overflow 8 seconds

4 Problems of Symbolic Web Testing and Attacks Hard to Implement Symbolic Execution Platform for Web MIT s Ardilla not in public and only for PHP Various number of Web platforms: PHP, JSP, Python, Perl, Ruby, ASP Variety of Attack Methods Non-web attacks: stack, heap, format, integer, uninitialized uses, race, OWASP top attacks: injection, XSS, CSRF,

5 Web Platform Independent Testing (PHP,JSP,ASP,NodeJS,Python,Ruby, ) symbolic execution engine? QEMU based symbolic execution engine -> S2E Issues Performance should be the primary consideration Will symbolic semantics be preserved? Across between Web semantics and llvm semantics.

6 Attack Independent Exploit Generation Taint Analysis Input tainted operations Symbolic Continuations (what to do next?) Symbolic program counter (Symbolic EIP) Where the EIP points to Symbolic SQL query Where the SQL commands run Symbolic HTML response Where the Javascript executes Symbolic command argument Where the shell commands run

7 The power of Symbolic Computation Symbolic Execution Generating Testing input, following all feasible branches Concolic Execution Generating Testing input, following a concrete input path and the associated branches Exploit Generation Generating Exploit input, following a concrete Crash/Anomaly input path and branch to the associated shell code Path Constraint generated by the crash input Constraints of Symbolic continuations branching to the shell code

8 Symbolic Execution Explore every possible path of a program Record path information in path constraint Path constraint 1 Symbolic input A program Path constraint 2 Path constraint 3 Liu Huan 劉歡 A Generic Web Testing 2014/2/11 8 and Attack Generation Framework

9 Concolic Execution Begin with a random input Use false path constraint to generate another input case Input 1 Input 2 A program Output1 Path constraint 1 Output2 Path constraint 2 Input 3 Output3 Path constraint 3 Liu Huan 劉歡 A Generic Web Testing 2014/2/11 9 and Attack Generation Framework

10 Exploit Generation Record the path constraint of the given crash input Crash Input: x A program Output: y Path constraint Liu Huan 劉歡 A Generic Web Testing 2014/2/11 10 and Attack Generation Framework

11 Constraint Solving Unknown input: x A program Output: y Path constraint Given program output y, constraint solving is the way to generate input x Output: y + Path constraint Solve constraint Value of input x 11

12 Constraint Solving If f(x) = 100, what s the value of x? Known output =100 Unknown input: x Sample code int f(x){ int y=x+10; if (y >0) return y; else return y; } 12

13 Constraint Solving If f(x) = 100, what s the value of x? Use symbolic execution to get path constraint PC of path 1 PC of path 2 Path constraint X+10 > 0 X+10 <= 0 Sample code int f(x){ int y=x+10; if (y >0) return y; else return y; } 13

14 Constraint Solving If f(x) = 100, what s the value of x? Use symbolic execution to get path constraint f(x) = y = X+10 = 100 Add path constraint X + 10 = 100 Known output =100 PC of path 1 PC of path 2 Path constraint X+10 > 0 X+10 <= 0 Add constraint from known information X+10 = 100 X + 10 = 100 Sample code int f(x){ int y=x+10; if (y >0) return y; else return y; } 14

15 Constraint Solving If f(x) = 100, what s the value of x? Use symbolic execution to get path constraint f(x) = y = X+10 = 100 Add path constraint X + 10 = 100 Solve the constraint x = 90 PC of path 1 PC of path 2 Path constraint X+10 > 0 X+10 <= 0 Add constraint from known information input: x=90 X+10 = 100 X + 10 = 100 Constraint solving X = 90 No solution Known output =100 Sample code int f(x){ int y=x+10; if (y >0) return y; else return y; } 15

16 Constraint Solving What s the XSS exploit of the given sample code? Sample code <?php $input = $_GET['id']; for($i=0; $i<strlen($input); $i++) echo chr(ord($input[$i])+1);?> 16

17 Constraint Solving What s the XSS exploit of the given sample code? Symbolic request & response HTTP Request Unknown input (XSS attack) GET /index.php?id=[ input ] HTTP/1.1 Host: example.com HTTP Response Known output (an alert script) HTTP/ OK Context-type: text/html <html> some text [ output ] </html> Sample code <?php $input = $_GET['id']; for($i=0; $i<strlen($input); $i++) echo chr(ord($input[$i])+1);?> 17

18 Constraint Solving What s the XSS exploit of the given sample code? Symbolic request & response Add JavaScript code as target character output = <script>alert(document.cookie)</script> HTTP Request ;rbqhos= GET /index.php?id=[ input ] HTTP/1.1 Host: example.com HTTP Response HTTP/ OK Context-type: text/html <html> some text [ output ] </html> <script> Sample code <?php $input = $_GET['id']; for($i=0; $i<strlen($input); $i++) echo chr(ord($input[$i])+1);?> 18

19 Constraint Solving What s the XSS exploit of given sample code? Symbolic request & response Add JavaScript code as target character output = <script>alert(document.cookie)</script> Solve the constraint input = ;rbqhos=`kds cnbtldms-bnnjhd(;,rbqhos= HTTP Request ;rbqhos= GET /index.php?id=[ input ] HTTP/1.1 Host: example.com HTTP Response HTTP/ OK Context-type: text/html <html> some text [ output ] </html> <script> Sample code <?php $input = $_GET['id']; for($i=0; $i<strlen($input); $i++) echo chr(ord($input[$i])+1);?> 19

20 Path Constraints Input Path constraint Target output Solved output input[0] chr(input[0]+1) < ; input[1] chr(input[1]+1) s r input[2] chr(input[2]+1) c b input[3] chr(input[3]+1) r q input[4] chr(input[4]+1) i h input[5] chr(input[5]+1) p o input[6] chr(input[6]+1) t s input[7] chr(input[7]+1) > = input[8] chr(input[8]+1) a ` input[9] chr(input[9]+1) l k 20

21 Exploit Generation of Single URL This method can check security risk of a single URL HTTP Response HTTP/ OK Context-type: text/html <script>alert(document.cookie)</script> <html> some text [ output ] </html> mysql_query admin or 1=1-- SELECT * FROM user WHERE user=[symbolic] 21

22 Exploit Generation Generate exploit of a web application 22

23 Single Path Concolic Execution In order to reduce the overhead on symbolic execution HTTP Request HTTP Request GET index.php?abc=[ Host: ] HTTP/1.1 GET index.php?abc=[aaaaa] HTTP/1.1 Host: Symbolic execution: Explore all possible paths Single path concolic execution: Only explore the path of the given input 23

24 Restriction 24

25 Outline Introduction Background Method Exploit Generation System Architecture Related Work Evaluation Conclusion and Future Work 25

26 System Architecture Symbolic Environment on S 2 E CRAXWeb Architecture CRAX Framework Detail of CRAXWeb Web Crawler Symbolic Request Sender Symbolic Data Sensor Exploit Generator 26

27 S 2 E (Selective Symbolic Execution) Symbolic data sender Exploit generator 27

28 S 2 E (Selective Symbolic Execution) Symbolic data sender For XSS attack Symbolic data sensor Exploit generator 28

29 S 2 E (Selective Symbolic Execution) Symbolic data sender Symbolic data sensor For SQL injection attack Exploit generator 29

30 CRAXWeb Architecture (server) QEMU S 2 E Test unit Web application Symbolic data sensor s2e_myop Sym. socket Web crawler Symbolic request sender Sym. Socket Web Server Expolit generator Report Sym. Socket Symbolic data sensor (client) s2e_myop STP Solver 30

31 CRAX Framework 31

32 Web Crawler (server) QEMU S 2 E Test unit Web application Symbolic data sensor s2e_myop Sym. socket Web crawler Symbolic request sender Sym. Socket Web Server Expolit generator Report Sym. Socket Symbolic data sensor (client) s2e_myop STP Solver 32

33 Web Crawler (Burp Suite) Web application GET index.php?abc=xxxxx HTTP/1.1 Host: example.com Web crawler Database POST index.php HTTP/1.1 Host: example.com Content-length: 40 a=xxxx&b=xxx 33

34 Symbolic Request Sender (server) QEMU S 2 E Test unit Web application Symbolic data sensor s2e_myop Sym. socket Web crawler Symbolic request sender Symbolic request sender Sym. Socket Web Server Sym. Socket Expolit generator Report Symbolic data sensor (client) s2e_myop STP Solver 34

35 Symbolic Data Sender Web crawler Database Control node 1. Experiment request 2. Experiment response Symbolic data sender Web application 2014/2/11 35

36 Symbolic Data Sensor Web application (server) Symbolic Symbolic data data sensor sensor Sym. socket QEMU s2e_myop S 2 E Test unit Web crawler Symbolic request sender Sym. Socket Web Server Expolit generator Report Sym. Socket Symbolic Symbolic data data sensor sensor (client) s2e_myop STP Solver 36

37 Symbolic Data Sensor Sensitive data Symbolic data sensor Exploit generator If it is a symbolic data, The sensor can call exploit generator Web security issues XSS SQL injection Sensor location HTTP Response mysql_query() 2014/2/11 37

38 Other Web Security issues Sensor location PHP Python Remote file Inclusion include(), include_once() include(), require() Directory fopen(), file() open() traversal Command system(), file() system(), exec() injection Code Injection eval() eval() File upload move_uploaded_file(), rename(), open() 38

39 Exploit Generator (server) QEMU S 2 E Test unit Web application Symbolic data sensor s2e_myop Sym. socket Web crawler Symbolic request sender Sym. Socket Web Server Exploit generator Expolit generator Report Sym. Socket Symbolic data sensor (client) s2e_myop STP Solver 39

40 Exploit Generator 2014/2/11 40

41 Exploit Generator SELECT * FROM user WHERE user=[symbolic] symbolic Sample code <?php $input = base64_decode($_get[ user']); mysql_query( SELECT * FROM user WHERE user=. $input);?>... x.php?user=ywrtaw4gb3ig... 41

42 Outline Introduction Background Method Related Work Evaluation Conclusion and Future Work 42

43 Front End Interface 43

44 Front End Interface 44

45 Experiment Monitor CRAX Web Guest QEMU 45

46 Generated Exploit 46

47 Exploit Validation 47

48 Exploit Validation 48

49 Evaluation for Web platform independence PHP JSP Rails Django ASP Framework OS Linux Linux Linux Linux Windows Server Apache Tomcat Webrick Built-in IIS-5.1 Kernel PHP JDK-7u2 Ruby Python ASP-3.0 Bind Port Symbolic response time Without constraints Test case ~= echo( A x50) OT >= 12hr 18.50s 6.72min 7.45min 32.72s OT 16.42s 3.25min 5.62min 24.02s OT 49

50 Test Case Test Case Evaluation for XSS Line Of Code # of crawled request # of XSS (vulnerable) # of XSS by MIT Time per exploit Time for all crawled request Schoolmate , min min + 30OT Webchess-1.0.0rc2 6, (4) min 94.38min + 313OT Faqforge , min 5.74 min EVE min 4.94min Line Of Code Platform # of crawled request # of XSS (vulnerabl e) Time per exploit Time for all crawled request SimpGB ,296 PHP 1,299 33(57) 0.91min 7.67hr + 334OT DedeCms ,544 PHP 1,111 11(13) 0.48min 8.32hr + 9OT Django-admin ,558 Python min 5.29min + 4OT Discuz! ,088 PHP 613 0(1) 0.85min 8.37hr + 12OT Joomla ,711 PHP 215 0(7) 2.17min 1.26hr + 117OT OT >= 15min 50

51 Evaluation for SQL injection Test Case Schoolmate 1.54 Webchess 1.0.0rc2 Faqforge EVE Testlink phprecipiebook 2.24 Line of code CVE # of crawled request # of SQLi (vulnerable) # of SQLi by MIT Time per exploit 0.55 min 0.39 min 0.27 min min 4.89min min Time for all crawled requests min min 1.88min 2.12 min 706.4min (30 TO) 315.2min (32 TO) # of all solved constraints TO: Timeout 51

52 Outline Introduction Background Method Related Work Evaluation Conclusion and Future Work 52

53 Automatic Web Attack Generator Based on symbolic execution White box Only support specific language Based on reply value of server Black box Hard to handle encrypted data 53

54 Related Work Approach year Attacks/ Detectd Generation Algorithm W/B Plateform Box SAFELI 2008 SQLI Attack Statically inspect bytecode of application WB JAVA Apollo 2008 Malformed HTML Use Concolic execution to find bugs in PHP WB PHP Detect web applications Adrilla 2009 XSS, SQLI Attack It combines concrete and symbolic WB PHP execution to covers paths Kudzu 2010 XSS, SQLI Attack Attack gramma and symbolic execution WB JavaScript PIUIVT 2010 XSS, SQLI Attack Perturbation based Algorithm WB Java MySQLInject 2011 SQLIJ Attack Blind SQL Injection based on True/False, BB PHP or Order by NKSI Scan 2012 SQLIJ Attack Modulize SQL Injection patten to generate BB JSP, ASP attack string CRAX Web 2012 XSS, SQLI Attack Single path symbolic execution WB XSS: All, SQLI: PHP 54

55 Related Work Approach Year Attacks / Detectd W / B Plateform Box SAFELI 2008 SQLI Attack W JAVA Apollo 2008 Malformed HTML W PHP Detect Adrilla 2009 XSS, SQLI Attack W PHP Kudzu 2010 XSS, SQLI Attack W JavaScript PIUIVT 2010 XSS, SQLI Attack W JAVA MySQLInjector 2011 SQLI Attack B PHP NKSI Scan 2012 SQLI Attack B JSP, ASP CRAX Web 2012 XSS, SQLI Attack W XSS: All, SQLI: PHP 55

56 Conclusion A framework to generate exploit of web application Support XSS and SQL injection Web application CRAX Web Vulnerability Report A successful trial of Symbolic Execution for Web by S2E 56

57 Future Work Implement this structure on other kind of exploit generation Other Web Security issues Remote file Inclusion / Local File Inclusion Directory traversal Command injection Code Injection File upload Target Functions include(), include_once(), require(), requireonce() fopen(), file(), unlink system(), file() eval() move_uploaded_file(), rename(), Liu Huan 劉歡 A Generic Web Testing 2014/2/11 57 and Attack Generation Framework

58 Open Doors to More Work Symbolic Executions by S2E for PHP, Python JSP, Ruby ASP, Perl Node JS