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Chapter 3 _ Security Part I _ Auditing Operating Systems and Networks.docx

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Chapter 3 – Security Part I – Auditing Operating Systems and Networks Overview  Principal threats to the OS and control techniques  Risks over intranet and internet  Risks associated with personal computing systems  Risks that arise in connection with EDI Auditing Operating systems  Computer’s control program  Allows users to share and access common computer resources (i.e. processors, databases) Operating system objectives  3 main tasks: translate computer language, allocate computer resources, manages tasks of scheduling  Jobs are sent to computer through: system operator, batch-job queues, and telecommunications  5 control objectives: protect from users, users to each other, users to themselves, itself, and environment Operating system security  Log-on procedure: requests for user ID and password  Access Token: contains information about user, user ID, password, and access privileges  Access Control list: database of who has access to what  Central system admin determines who has access. In distributed systems, end users manage themselves Threats to operating system integrity  3 threats: privileged personnel who abuse their authority, those who seek to exploit security flaws, those who intentionally insert destructive programs into operating systems Operating System controls and audit tests o Audit objectives: verify that access privileges are granted in a manner that is consistent with separating incompatible functions and in accordance with organization’s policy o Audit procedures: review org policies for separation, match job descriptions to access, review if there was a security check on employees, permitted log- on times  Contra security to passwords: forgetting, failing to change, post-it syndrome, simple passwords  Two way password: pin + keypad (physical) o Audit objectives re passwords: adequate and effective password policy o Audit procedures: verify if policies are being followed o Audit objectives re virus: strict policies and procedures against virus infections o Audit procedures: observe that operations personnel have been educated about computer viruses, verify that current antiviral software, new software is tested on isolated workstations first  System audit trails are logs that record activity  Keystroke monitoring: recording user’s keystrokes and the system’s responses  Event monitoring: summarizes key activities related to system resources (i.e. who accessed the system and when) o Audit objectives: detecting authorized access, facilitating reconstruction of events, and promoting accountability o Audit procedures: ensure audit trail is active, scan log for unusual activity and look into follow-up activity Intranet risks  Consists of small LANs and large WANs  Used to connect employees  Reasons to be a threat: vengeance, desire for a challenge, profit from selling secrets  Sniffing: unauthorized interception of information by a node on a network  Reluctance to prosecute: too embarrassed to admit breach of security but new legal obligation to disclose for negligent hiring liability Internet risks  IP spoofing: masquerading IP to gain unauthorized access  Denial of service attack (DOS): attacking a website so it does not have capacity to service others o SYN flood: 3- way handshake. Attacker sends syn, victim responds with ack, but attacker doesn’t complete with the syn-ack  How to protect? Use a firewall if IP can be traced o Smurf attack: perpetrator sends a request to an intermediary that sends multiple attacks to the victim o Distributed denial of service (DDos): similar to syn flood or smurf but uses a IRC (internet relay chat) to source for zombies and increase the attack Controlling risks from subversive threats  Firewalls: a system that prevents access between two networks o Network-level: examines source and its destination o Application-level: run proxies o Most have dual-home systems: one to screen incoming requests from the internet and other to provide access to the intranet
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