Vulnerability: a flaw or weakness that can be exploited by attackers to compromise the security of a system


  • Confidentiality: keeping data secret
  • Integrity: unauthorized users should not be able to modify data
  • Availability: nobody can disturb the system i.e. with (D)DOS attacks

TCB (Trusted Computing Base): the hardware and software to enforce the security rules. Linux/Windows have monolithic architecture so the TCB consists of all code running in the kernel Reference monitor: makes all security decisions for system calls checks the security rules

Protection domain: specifies which operations are allowed on objects

Optimal security: when each domain is equipped with the minimum necessary objects and privileges to fulfill its function

Protection matrix is big ACL (Access Control Lists): each object stores a list domains that can access the object of e.g. for every file store the users can access it (colomn of matrix) Capability: domain and all the rights they have (rows of matrix)

Insider attacks:

  • Logic bombs: malicious code intersted by insiders
  • Back doors
  • Login spoofing: