Web Services Security A Survey Abu Uddin

Web Services Security – A Survey Abu Uddin Shamual Rahaman 1

Web Services n Open standard (XML, SOAP, etc. ) based Web applications that interact with other web applications for the purpose of exchanging data. n Initially used for the exchange of data on large private enterprise networks, web services are evolving to include transactions over the public Internet. n Even though it’s framework in not 100% complete, people have been widely using it. n Heterogeneous, loosely coupled architecture. 2

Hello Web Services 3

Hello Web Services 4

Hello Web Services 5

Web Services Security n Importance of security in Web Services. n Security Issues in Web Services. n Our Survey. 6

Selected Papers n Threats and security of Web services - a theoretical short study -Rao, Radha Krishna n Web service security - vulnerabilities and threats within the context of WS-security -Holgersson, J. ; Soderstrom, E. ; n Web Service Composition: A Security Perspective -Carminati, B. ; Ferrari, E. ; Hung, P. C. K. ; n Algorithm Exchange of a Security Control System for Web Services Applications -Nasution, B. B. ; Kendall, E. A. ; Khan, A. I. ; 7

Paper 1: Threats and security of Web services - a theoretical short study n Various threats and remedies for web services. n This paper mainly focuses mainly on three different attacks: Dictionary Attack, Replay Attack, and Buffer Overflow. n Vital points in Web services security: Authentication n Authorization n Confidentiality n Integrity n Non-repudiation All of these can be satisfied by using encryption except Authorization, where it can use SOAP messages. n 8

Dictionary Attack n Reverse Turing Test. n was developed to protect system from automated program that launches dictionary attack. n combine the traditional password authentication with a challenge that is very easy to answer for a human but not possible for an automated program. n widely used by many web sites, such as Hotmail, Yahoo. 9

Dictionary Attack n Advantages of Reverse Turing Test: n n n does not affect the usability. offers a much better protection. no special hardware or software is needed to implement. n Disadvantages of Reverse Turing Test: n n requires certain capabilities on the user side. can frighten the user who are unwilling to solve the riddles. can affect the scalability of the system. not optimal for large scale system. 10

Dictionary Attacks n Java Cryptography: Dictionary attacks take twice the time to break a simple protection algorithm than doubly protected password. n now used in various critical applications. n Java Cryptography Architecture(JCA) n Java Cryptography Advantages: n Portability n permits controlled execution of less trusted code (vs. Activex) n fine grained permission control n n Java Cryptography Disadvantages: n n complex dependencies on other system, OS, browser, network(DNS), PKI flexible policies accepted by user may permit hidden breaching interactions. 11

Dictionary Attacks n Secure Socket Layer (SSL): n most popular transport layer security protocol for internet. n offers the basic security services of encryption, source authentication and integrity protection for data exchanged over underlying unprotected networks. n Many product and OS has support for SSL. Also many web services permits the SSL communication. n SSL has all available security functions that’s needed to make a project secure (authentication, asymmetric/symmetric encryption, MAC and certificates). n But the problem with SSL is that programmers have to know a lot of details about the OS, and system calls. 12

Replay Attack n When an attacker simply listens and sniffs the packets and then later he resends the same packet, it’s called replay attack. n The intruder might extract information and alter or inject his own information in the message stream. n easier to detect with Web Services. 13

Buffer Overflow n Buffer Overflow is one of the major threats on data integrity. n Some of the solutions to the buffer overflow problem are: n n n Applying patch to the affected code that will check the length of the data before saving it to the buffer. Apply backup code to replace the overflowed one to gain back authorities of the system. Use programming languages that has automatic bound checking. 14

Paper 2: Web Service Security – Vulnerability And Threats within the context of WSSecurity n The security issues in Web Services n Threats involved n Incompatibility of traditional Security techniques n WS-Security Basics n WS-Security vs. Web Services Threats 15

Security Issues n Security of the information must be provided while the information is in transit and while it is in storage of the server n Similar criterion as of traditional security must be satisfied 16

Security Issues n Confidentiality n Integrity n Non-repudiation n Authentication n Authorization n Availability 17

The threats n Maintaining Security while Routing n Unauthorized access n Parameter manipulation/malicious input n Eavesdropping and Message Replay n Denial of Service (Do. S) n Bypassing of Firewalls n Immaturity of the platform 18

Short comings of Traditional Security mechanism n Traditional Security techniques works on the Lower level of the OSI stack of message transfer n Doesn’t provide security against Application level communication 19

OSI Stack 20

WS-Security n Is a new security standard n Published in April 2004 n Still incomplete but promising 21

WS-Security Basics n Adds security to the SOAP message n Passes the security information in the Header of the SOAP Message n 3 Basic Elements Security tokens n XML Encryption n XML Signature n 22

WS-Security, Tokens n Tokens are the security artifact included in a SOAP message n Provide authentication and authorization n Can use simple user id and password based authentication n Also capable of advanced certificate based authentication like X. 509 23

XML Encryption n A specification developed by W 3 C n Prevents unauthorized access to the XML document n Require a decryption key to read the Document n Different part of the document may require different key to decrypt 24

XML Encryption n Therefore XML Encrypted Document can have multiple recipients n Each recipient will use their own decryption key without violating the privacy of others 25

XML Signature n Also developed by W 3 C n Serves the same purpose that of a traditional signature n Authenticates the credentials of the token n This provides message integrity n Just like XML Encryption different part of the document may have different signature associated with it 26

WS-Security VS Threats Remember the threats…. . n n n n Maintaining Security while Routing Unauthorized access Parameter manipulation/malicious input Eavesdropping and Message Replay Denial of Service (Do. S) Bypassing of Firewalls Immaturity of the platform n All of them satisfied except n Denial of Service n Bypassing of firewalls n Immaturity of the platform 27

Ws-Security: The Road Map 28

Paper 3: Web Service Composition: A security Perspective n The papers describes a security conscious Web Service composition framework that supports different security requirement criterion imposed by different WS provider and requestor 29

Web Service Composition 30

Composition With Security Restrictions n Different WS may have different security requirement e. g. some WS may require the X. 509 based authentication as a security measurement for authentication and authorization n Some service requestor may want his service to be processed by a WS that use P 3 P based privacy policy 31

Secure WS Broker Architecture Image ref [3] 32

Secure WS Broker Architecture n Four main components n Modeler n Web Services Locator n Security Match Maker n WSBPEL Generator 33

SWS Broker: Modeler n Given the service request try to build a work flow n For example given a task A The modeler tries to divide the task in a sequence of tasks say {A 1, A 2, A 3, A 4} which must be carried in sequence n The A 1, A 2 etc are the activities 34

SWS Broker: SWs Locator n The locator is actually a simple old fashioned Web Service locator that finds the Web Services that capable of servicing the request n The locator finds all the sets of Web Services that are capable of servicing A 1, A 2 etc. 35

SWS Broker: Match Maker n This is the model that employs the security constrains imposed by all the involved Web Service Providers and Requestors n The algorithm is explained with an example in the next slide 36

Match Maker: Algorithm/Methodology n Lets say the service locator provides the following WSs for each of the activities in previous example 37

Match Maker: Algorithm/Methodology n We can build a following tree structure for the Wss. (Figure ref [3]) 38

SWS Broker: WSBPEL n Web Service Business Process Execution Language n Beyond the scope of this Paper 39

Defining Security Requirement n All the previously mentioned techniques sounds easy n But how to search and compare security requirement and Constraints n WSDL, SOAP none provides such mechanism 40

Modeling Security Information n Two Classes n Capability Description n Constraint Description n Compatibility General Final 41

Capabilities Description n Uses SAML description of following type (Figure ref [3]) 42

Compatibility Constraint Description n Compatibility Constraints can be put into the WSDL using the extensibility element of WSDL 43

Other Constraint Description n The other two constraint criterion general constraint and final constraint goes into the SOAP definition 44

Future Work n The author working on implementing additional constraints like quality of service constraints n They are trying to produce a better version of the Match Maker Algorithm 45

Paper 4: Algorithm Exchange of a Security Control System for Web Services Applications n Problem with WS-Security standard. n This papers takes system approach rather than analytical approach. n Two parts of the paper: TTSN(Trusted Tansient Simple Network) Architecture. n Algorithm Exchange. n 46

Trusted Transient Simple Network n 3 rd parties in web services. n it is necessary for each party to provide itself with a sophisticated security system which can be very independently of any other middle parties. n The most frequent strategies to solve the security problem have mainly focused on already known risks. But such strategy will fail when an unknown risk occurs. 47

TTSN n TTSN General Architecture: n The traffic package leaving from A through one path will be sent back to B through the other path. n Also, B will also append the reversed traffic package to B with the response. n In this way, A will know enough information regarding the state of the transaction and some behavior of its counterpart. n Can be activated/deactivated dynamically 48

TTSN n TTSN Security control system: n n Plant of the control system. If the plant is not stable, A must maintain the process in a continuous stable state. 49

TTSN n The reasoning mechanism. n Interdependency of all security properties: n Each property will be occupied by an intelligent agent. 50

TTSN n TTSN’s main modules: 51

TTSN n By deploying co-operative intelligent agents, loosely coupled interrelationship and strong definition of policy and rules, the aim is that TTSN will be able to solve and handle any current and potentially new vulnerability and threats. 52

Algorithm Exchange: n Since web services performs XML-based transactions and most n n n internet transaction perform secret key exchange, it is very likely to be intercepted. The interceptor has a chance of cracking the content of the message sooner or later. TTSN performs algorithm exchange instead of key exchange. Both parties dynamically exchanges their algorithm throughout the session. Since both parties used their unique algorithm, the authors claimed that, it will be really difficult, if at all possible, for the interceptor to crack the message performing a brute force analysis to the algorithm, NOT to the key. no known techniques available to crack algorithm. 53

Algorithm Exchange n Reflection packages and serialized class features of JAVA. n Java class file issue. n this method not only guarantee confidentiality, but also authentication and message integrity. Since the algorithm is not known, any one else cannot impersonate the sender. n The recipient must deploy the previous algorithm to check the integrity of the data validating the signature. n 54

Implementation/Testing Methodology: n The authors have successfully implemented and tested a cryptographic algorithm exchange in a web service environment using IMB Web. Sphere Studio Device Developer(WSDD 5. 6) and JDK 1. 4. 1 55

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Implementation/Testing Methodology: n After the class was loaded it has been instantiated and the method has been extracted and invoked: 61

Comparison with other/similar technology n On first glance, Algorithm Exchange looks like the mechanism of IPSec or Opportunistic Encryption. n On IPSec all algorithm must comply with IETF’s standards, which are very common (DES, Triple. DES, RC 4 etc). A node cannot be embbeded with user’s own generated algorithm. n In Opportunistic Encryption nodes do not exchange algorithms, but they still exchange keys. n IPSec handles network-layer security to protect transactions from hardware or OS level attackers, while most security in web services deals with threats on higher level than IP layers, most of which are software level attackers. n No programming language other than Java can dynamically load a computer program during runtime. Object serialization and class reflection made such thing possible. 62

Conclusion n Web Services is yet not matured. n Web Services Security is still infant. n Our 4 papers. 63

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