S-Scrum: a Secure Methodology for Agile Development of Web Services

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1 Worl of Computer Siene n Informtion Tehnology Journl (WCSIT) ISSN: Vol. 3, No. 1, 15-19, 2013 S-Srum: Seure Methoology for Agile Development of We Servies Dvou Mougouei, Nor Fzli Moh Sni, Mohmm Moein Almsi Deprtment of Informtion System Fulty of Computer Siene n Informtion Tehnology Universiti Putr Mlysi, Serng, Selngor, Mlysi Astrt Wiely use in evelopment of we servies, Srum ontriutes to gile servie evelopment, reuing the Time To Mrket (TTM) n inresing the profit to servie proviers. Cring for ynmi requirement hnges n inrementl evelopment of we servies re other vntges of employing Srum for evelopment of we servies. However there re severl prolems with this methoology limiting its ppliility to we servie evelopment. Srum overlooks preise oumenttion of evelopment tivities to inrese the evelopment spee. Nonetheless this pproh negtively ffets the qulity of the we servies through inorporting impreision n lk of trtility into the evelopment proess. On the other hn seurity s qulity ttriute hs lwys een one of the most importnt onerns of the we servie evelopment. To re for seurity of the we servie we lwys nee to inorporte seurity nlysis n esign into the evelopment life yle. Although there hve een some ttempts to re for nlysis tivities within the Srum itertions, it is not ler yet how to hieve this utomtilly through the Srum proesses. On the other wors reful engineering of seurity into the overll system nlysis n esign is often neglete. In this pper we propose seurity-enhne version of srum i.e. Seure Srum (S-Srum) to ommote seurity nlysis n esign tivities within the Srum. We hve moifie the sum proess to re for seurity nlysis n esign through the stnr Sum proesses. The vliity of the propose pproh is verifie through forml moeling n esription of the proess steps. We propose grmmr for forml esription of Sum proess moel. Keywors-Srum; We Servie; Seurity; Automt. I. INTRODUCTION The inresing emn for rpi evelopment of we servies hs le to wiely use of gile methoologies to filitte rpi servie ientifition n extrtion of we servies from legy systems [1]. On the other hn seurity of we servie hs eome ig onern of we servie evelopment. The importne of seurity is more tngile when it omes to signifint [2] we servies expose glolly over the we. Srum s n gile methoology llows for rpi evelopment of we servies. Srum lso llows for keeping rest of the hnging requirements uring the softwre evelopment [3]. Evolutionry nture of Srum proess lso filittes inrementl evelopment of we servies se on user requirements n mrket emn. However srum is ritiize for negleting seurity nlysis n esign through the evelopment proesses [4]. In this regr, Srum is not proper for seure softwre evelopment [4] sine it oes not expliitly speify tivities for seurity nlysis n esign require for seure softwre evelopment [5]. To ssure seurity of the we servies it is require to present stuffiest ouments proving stisftion of seurity ojetives [4]. Seurity ssurne is not properly supporte in Srum ue to the overlooking oumenttion of seurity onsiertions n nlysis results. Negleting the seurity oumenttion or eemphsizing on oumenttion tivtes, is quiet risky in the ontext of eveloping seurity ritil system [6]. Lk of seurity oumenttion lso mkes it iffiult to opt seurity stnrs suh s Seure Systems Engineering Cpility Mturity Moel (SSE-CMM) [7] in srum. SSE-CMM is esigne to mesure pilities of the orgniztion for eveloping seure softwre. Compre to SSE-CMM, Srum oes not re for essentil seurity tivities suh s impt ssessment, seurity risk ssessment, thret ientifition n vulnerility nlysis. Srum proess lso oes not support ssurne uiling n seurity monitoring tivities [4]. Forml n ler speifition of we servies s Seurity Critil Systems (SCSs) in the erly stges of softwre evelopment les to more seure we servies [5]. On the other hn teious oumenttion tivities require y tritionl methoologies reue the gility n ompromises the enefits of Srum. To support seurity ssurne in Srum lightweight oumenttion is require to properly reflet the 15

2 seurity spets of the system [2] while mintining the enefits of Srum. Suh oumenttion must e proue through trele nlysis n esign tivities inorporte into the Srum. Integrte into the Srum, suh metho must e simple, omptile with gile evelopment n not interepting the regulr Srum tivities [3]. In orer to e suessfully integrte into the Srum, suh metho must speify ll seurity onsiertions throughout the evelopment tivities. Although there hve een some ttempts to re for nlysis tivities within the Srum itertions suh s pplying spikes [8], it is not yet ler how to hieve this utomtilly through the Srum proesses. Spikes re introue to ommote evelopment tivities whih o not proue ustomer-vlue prouts. However, it is not speifie how to effiiently perform spiking n unle the spikes to the srum proess tivities. In this pper we propose seurity-enhne version of Srum i.e. Seure Srum (S-Srum) to inorporte seurity nlysis n esign tivities into the Srum proesses. Our im is to enle using Srum for evelopment of seurity ritil we servies. The propose methoology resses nlysis n esign of seurity nees within the erly stges of softwre evelopment throughout onstrutive pproh. We hve moifie the srum proesses to ommote oumenttion tives whih reflet the seurity spets of the trget we servie. Our propose methoology properly res for oth seurity n lso hnging requirements uring the relese plnning, sprints n spikes. Spikes re properly employe in S-Srum to ommote nlysis, esign n etile esign tivities for seurity requirements. We illustrte the proess steps through forml moeling of the S- Srum. Non-eterministi finite utomtons re use to emonstrte the proess steps n trnsition mong them. We lso hve propose ontext free grmmr for forml esription of proess steps. The reminer of the pper is orgnize s follows. Setion II presents our propose methoology. In Setion III we ring the forml moel of the propose methoology n esrie the propose grmmr. Setion IV of the pper shows the vliity of our pproh through pplying it to running exmple. Pper will e onlue in setion V with some generl remrks. WCSIT 3 (1), 15-19, 2013 II. THE PROPOSED METHODOLOGY The propose methoology onfirms to the stnr srum proess s epite in Figure 1. The proess strts with inititing the prout klog. Then the proess ontinues in two simultneous rnhes. The first proess strts story gthering to re for hnge in requirements me y stkeholers. The inoming hnges will e kept in the witing list till the strt of next spring unless the hnge hs ruil effet on the implementtion of the we servie. In this se we terminte the urrent relese proess n strt gin from relese plnning step. Figure 1. S-Srum proess After relese plnning spike for seurity nlysis will e performe n fter tht prout klog my e upte. The proess then ontinues with performing seurity moeling in next spike. In this stge the results of the seurity nlysis will e reflete into the moel of urrent relese prout items. The high priority prout items will e hosen then uring the sprint plnning to e implemente uring the sprint. However 16

3 we still nee to inorporte etils of seurity nlysis into the moel of these selete items within the etile esign spike. The proess will e followe y implementing, testing n emo [8] of the urrent sprint s prout items. As stnr srum prtie, if the stories re omplemente n epte y qulity ssurne unit, the relese will e onute. Otherwise more sprints will e require to resolve the issues. The proess ontinues till to the point ll stories re implemente. Sine our fous in this work is more to inorporte the seurity onsiertions into the srum proess, penetrtion test or similr seurity testing my e onute within the test stge. In this work we re not going to propose seurity nlysis tehniques for seurity nlysis n esign stges. However ll possile seurity rtifts inluing misuse se [9] igrms my e use for this purpose. All the proess steps re epite in Figure 1. WCSIT 3 (1), 15-19, 2013 III. FORMAL MODEL OF THE PROPOSED METHODOLOGY To filitte further nlysis of the evelopment proess, we present forml representtion of S-Srum. For this purpose, we moel the proess using non-eterministi finite utomtons n using ontext free grmmrs. Figure 2 emonstrtes the si utomton moel of the S-Srum. Tle 1 esries the lels use in Figure 2. TABLE I. STATES IN S-SCRUM AYTOMATON Stte/Non terminl A B C D E F G Desription Spike 1(nlysis) Spike 2(moeling) Sprint Lst Sprint Relese New Requirement Bklog Upte As epite in Figure 2, we hve formlly moele the S- Srum proess strting with the first spike i.e. seurity nlysis spike. The first spike s given in TABLE I is represente s stte A whih is the initil stte of the utomt in Figure 2. The propose grmmr for esription of S-Srum proess is formulte in TABLE III. proess strts with inititing the prout klog. Then the proess ontinues in two simultneous rnhes. The first proess strts story gthering to re for hnge in requirements me y stkeholers. The inoming hnges will e kept in the witing list till the strt of next spring unless the hnge hs ruil effet on the implementtion of the we servie. In this se we terminte the urrent relese proess n strt gin from relese plnning step. After relese plnning spike for seurity nlysis will e performe n fter tht prout klog my e upte. The proess then ontinues with performing seurity moeling in next spike. In Figure 2. Automt moel for S-Srum TABLE II. TRANSITION LABELES IN S-SCRUM AYTOMATON Terminls e f g h Desription Seurity nlysis one Seurity moeling one Stories implemente Finlize New relese New requirement New requirement Prioritize Bklog upte In this stge the results of the seurity nlysis will e reflete into the moel of urrent relese prout items. The high priority prout items will e hosen uring the sprint plnning to e implemente uring the sprint. However, we still nee to inorporte etils of seurity nlysis into the moel of these selete items within the etile esign spike. The proess will e followe y implementing, testing n emo [8] of the urrent sprint s prout items. As stnr srum prtie, if the stories re omplemente n epte y qulity ssurne unit, the relese will e onute otherwise more sprints will e require to resolve the issues. The proess ontinues till to the point ll stories re implemente. Sine our fous in this work is more to inorporte the seurity onsiertions into the srum proess, penetrtion test or similr seurity testing my e onute within the test stge. In this work we re not going to propose seurity nlysis tehniques for seurity nlysis n esign stges. However ll possile seurity rtifts inluing misuse se [9] igrms my e use for this purpose. All the proess steps re epite in Figure 1. 17

4 WCSIT 3 (1), 15-19, 2013 The proution rules for the propose grmmr lso re given in Tle III. TABLE III. PRODUCTION RULES IV. Rules P1: A BD ff P2: B C ff P3: C C λ P4: D E P5: E ea λ P6: F gg P7: G ha RUNNING EXCAMPLE We hve emonstrte the vliity of our pproh y pplying it to si senrio for implementtion of seurity requirements in money trnsfer we servie. The senrio is s follows. The evelopment tem ims to evelop seurity requirements of Money Trnsfer Servie (MTS) using srum s the evelopment methoology. MTS is esrie s follows: OBS provies some stnr nking servies inluing money trnsfer servie over the internet. The nk ounts re tempting trget for hkers. For this reson, MTS trnstions must e protete to keep finnil losses to minimum. The vilility of MTS is s importnt s the onfientility n integrity. The MTS lso hs server whih shoul e protete from ny possile misuse. In ition to tht, n ttker my exploit the MTS internl ommunition network to threten the trnstions. MTS in ition shoul prevent unuthorize online ess to the servie. Thus, it supports user uthentition y heking the user nme n psswor. However, the ttker still n guess either user nme or psswor ut it is suppose to e iffiult. MTS must offer resonle ssurne tht their ustomers ounts re seure. The min thret tht onerns MTS is tht n ttker will trnsfer money out of ustomers ounts. The result of seurity nlysis for MTS se on [10] is emonstrte in Figure 3. During the srum proess the evelopment tem implements the requirements R n R uring the first relese. The two seurity requirements R n R will e ske y stkeholers to e implemente uring the seon relese of the prout. The tivities require to implement the seurity requirements for MTS re liste in Tle IV. TABLE IV. PROCESS ACTVITIES FOR MTSSECURITY IMPLEMENTATION Terminls e f g h V. CONCLUSION Desription Performing seurity nlysis for MTS Conuting seurity moeling of MTS Implementtion of seurity requirement of MTS First relese of MTS New relese for MTS Ctering for the new requirements of 1. Form fiel mnipultion 2. Query string mnipultion Prioritiztion of requirements tke ple Proee to upte klog Anlyze new requirements Design new requirements Implementtion of new requirements Seon relese of MTS inlues new requirements This pper hs propose seurity-enhne version of Srum i.e. Seure Srum (S-Srum) to inorporte seurity nlysis n esign tivities into the Srum proesses. The propose methoology hs moifie the srum proesses to ommote oumenttion tives whih reflet the seurity spets of the trget we servie. Our propose methoology res for oth seurity n lso hnging requirements uring the relese plnning, sprints n spikes. We illustrte the proess steps through forml moeling of the S-Srum. Noneterministi finite utomtons re use to emonstrte the proess steps n trnsition mong them. We lso hve propose ontext free grmmr for forml esription of proess steps. The propose methoology is prtilly moele n pplie on typil senrio for evelopment of money trnsfer servie to show the vliity of our pproh. 18

5 WCSIT 3 (1), 15-19, 2013 Figure 3. MTS seurity requirement moel for form fiel mnipultion n query string mnipultion REFERENCES [1] S. Chung, D. H. Won, S.-H. Beg, n S. Prk, "A Moel-Driven Srum Proess for Servie-Oriente Softwre Reengineering: msrum4sosr," in Computer Siene n its Applitions, CSA '09.2n Interntionl Conferene on, e,2009, pp.1-8. [2] H. Chivers, R. Pige, n X. Ge, "Agile Seurity Using n Inrementl Seurity Arhiteture," in Extreme Progrmming n Agile Proesses in Softwre Engineering vol. 3556, H. Bumeister, M. Mrhesi, n M. Holome, Es., e: Springer Berlin / Heielerg, 2005, pp [3] M. U. Kumr, D. S. Kumr, B. P. Rni, K. V. Ro, A. V. K. Prs, n D. Shrvni, "Depenle Solutions Design y Agile Moele Lyere Seurity Arhitetures," in Avnes in Computer Siene n Informtion Tehnology. Networks n Communitions vol. 84, N. Meghnthn, N. Chki, D. Ngmli, O. Akn, P. Bellvist, J. Co, F. Dressler, D. Ferrri, M. Gerl, H. Koyshi, S. Plzzo, S. Shni, X. S. Shen, M. Stn, J. Xiohu, A. Zomy, n G. Coulson, Es., e: Springer Berlin Heielerg, 2012, pp [4] J. Wäyrynen, M. Boén, n G. Boström, "Seurity Engineering n extreme Progrmming: An Impossile Mrrige?," in Extreme Progrmming n Agile Methos - XP/Agile Universe 2004 vol. 3134, C. Znnier, H. Erogmus, n L. Linstrom, Es., e: Springer Berlin / Heielerg, 2004, pp [5] J. Vieg n G. MGrw, Builing seure softwre: how to voi seurity prolems the right wy: Aison-Wesley, [6] B. Boehm, "Get Rey for Agile Methos, with Cre," Computer, vol. 35, pp , [7] F. Jos, B. Nunes, A. D. Belhior, n A. B. Aluquerque, "Seurity Engineering Approh to Support Softwre Seurity," presente t the Proeeings of the th Worl Congress on Servies, [8] S. Resnik, A. Bjork, n M. e l Mz, "Professionl Srum with Tem Fountion Server 2010," [9] T. Loerstet, D. A. Bsin, n J. u. Doser, "SeureUML: A UML- Bse Moeling Lnguge for Moel-Driven Seurity," in Proeeings of the 5th Interntionl Conferene on The Unifie Moeling Lnguge, e. Lonon, UK, UK: Springer-Verlg, pp [10] M. M. D. Mougouei, S. Mormn, "A Gol-Bse Moeling Approh to Develop Seurity Requirements of Fult Tolernt Seurity- Critil Systems," in 4th Interntionl Conferene on Computer n Communition Engineering, e. Mlysi,