TKK | Networking Laboratory | Studies | S-38.153

S-38.153: Answers for May 2005 exam

Answers for May 2005 exam.

1. 1. As the shutdown expences are 50.000 €, the internet shop must be quite large one with large amount financial and personal details online. In this case to protect company reputation, quick shutdown is reasonable choise. There may be a difference if sensitive information is only on (still safe) backend services. Many questioned absense of immdeiate backup server.
   2. One solution is to prohibit access from internal server to other servers expect to anti-virus companies. If company web servers are vulnerable, it may be vice to block external access to those also, unless thay are easily replaceable.
   3. The cheapest solution is to try educating users to select better passwords (and enforcing good passwords) and that can be tried as the first step. (Notifying users about bad passwords may create new security problems.) However, the expence for devices is not too great to be econimically feasible (with additiona high-tech factor).
2. Security model is explained in article "UMTS Security" (and on slides). Essential points were explaining mutual authentication, secure agreement on communication parameters, use of TMSI, authentication quintet. GSM compatibility makes possible to use fake base stations.
3. The most serious mistake was using third-party system to log in other system. Also having a large number of services and providing shell-access for developers to a single host as well as failure to update vulnerable services contributed to compromise. On-line host-based IDS would have identified attack on Sourceforge (so apache.org compromise would not happen); also one in apache.org would have detected attack earlier.
4. Network (packet, steteful, application-level) and host-based firewalls. Between different policies: internet-intranet, different departments, public services etc.
5. Quite often it was no considered what information is public or available by other means. Also for some cases availability and integrity is far more important that confidentiality (like with diabetes). Call records and email server logs, for example must have high level of confientiality; and call records high integrity for nbilling purposes. Routing table content and list of authorative name servers is not secret, but its imporant to have proper integrity. Router configuration is confidential as it may contain keys or passords.