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20100309 04 - Signature (McCabe)

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Isolating security threats

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20100309 04 - Signature (McCabe)

  1. 1. ISOLATING SECURITY THREATS Thomas J McCabe McCabe Technology tom@mccabetech.com copyright c March 9 2010 McCabe Technology
  2. 2. VOICI L'IDÉE  Etant donnée une menace cachée pour la sécurité et son chemin associé, nous pouvons profiter du fait même qu'elle soit cachée. De manière incrémentale, nous pouvons commencer par la menace et soustraire les bons chemins qui l'entourent, un par un --- ce qui précise de manière incrementale le sous-chemin fautif, c'est sa signature. Ou nous pouvons obtenir la signature de la menace par l'exécution de tous les chemins cyclomatic par soustraction des bons --- laissant la signature faute absolue.  La faille de sécurité pouvant être cachée dans des codes source très complexes et alambiqué fait qu'il est pratiquement impossible de trouver par inspection ---- ce que permet la technique présentée ici. copyright c March 9 2010 McCabe Technology
  3. 3. CONTEXT Many security flaws are compiled and obscured and within the source code when cyclomatic and essential complexity are very high; the inspection process breaks down. The signature method proposed here is one of the few realistic ways of detecting such hidden flaws copyright c March 9 2010 McCabe Technology
  4. 4. DEFINITION OF THREAT SIGNATURE copyright c March 9 2010 McCabe Technology
  5. 5. SMALL EXAMPLE  / * 1 * / if (active user)  / * 2 * / if (my flag)  / * 3 * / re_input(password,N)  / * 3 * / write(myfile,N)  / * 4 * / endif  / * 5 * / endif copyright c March 9 2010 McCabe Technology
  6. 6. REDUCING THE SIGNATURE  The good test 1-2-4-5 eliminates the edges (1,2) and (4,5) from the original signature  The reduced signature is the subgraph ((2,3),(3,4)) copyright c March 9 2010 McCabe Technology
  7. 7. SUCCESSIVE GOOD TESTS WILL SUBSET THE SIGNATURE copyright c March 9 2010 McCabe Technology
  8. 8. SIGNATURE UPDATE RULE copyright c March 9 2010 McCabe Technology
  9. 9. ORIGINAL FLAW copyright c March 9 2010 McCabe Technology
  10. 10. REFINING THE FAULT LOCALE 2ND TEST ELIMINATES (1,2) AND (11,12)copyright c March 9 2010 McCabe Technology
  11. 11. REDUCING THE FAULT LOCAL (CON’T) 3RD TEST (GOOD) REDUCED LOCALE copyright c March 9 2010 McCabe Technology
  12. 12. ROBUST EXAMPLE copyright c March 9 2010 McCabe Technology
  13. 13. 2ND TEST(GOOD) copyright c March 9 2010 McCabe Technology
  14. 14. WHAT WOULD YOU RUN NEXT? ORIGINAL FLAW SIGNATURE REDUCED FLAW SIGNATURE copyright c March 9 2010 McCabe Technology
  15. 15. GENERALIZING TO MULTIPLE FAULTS copyright c March 9 2010 McCabe Technology
  16. 16. SIGNATURE TECHNOLOGY ACROSS ARCHITECTURE  Highlights modules a fault traverses  Highlights modules containing signature  Highlights modules having absolute signature  Highlights signature edges within modules copyright c March 9 2010 McCabe Technology
  17. 17. OTHER APPLICATIONS  Business rule extraction  Reengineering  Localizing nasty bugs copyright c March 9 2010 McCabe Technology

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