In many network environments the administrators and security engineers have an understanding of the full geographical scope and reach of their network. While some corporations have a global audience and expect traffic from the far reaches of the world, others are more localized and target a specific small region.
A health care provider for Alaska would monitor its network connections to ensure that network connections are limited to its main source of users, i.e. those in Alaska. An insurance company in St. Louis will see mostly traffic from IP addresses in Missouri, but Illinois as well, due to the city being on the state line.
Occasionally, administrators may notice connections being made from Hawaii, Bermuda, or Italy, signifying users who are on vacation but are still wired in to their work. However, a long-term series of connections from a Eircom subscriber, Ireland’s largest ISP, should spark interest to the network administrator of a Seattle tax firm.
While anonymous web connections from global addresses are common, specific attention should be paid to such addresses being used to access password-protected areas of a corporation. This could include remote file access, VPN and web-based corporate email.
In such cases the logs from these applications, usually supplied in plain text or W3C format, contain details about transactions to include the remote IP address and the account name being authorized. In reviewing logs from various incident responses cmdLabs has found details to show that a short log review made on a daily basis could help smaller corporations determine quickly if a user account was compromised and accessed from a remote location.
For example, the log sample below from a Cisco ASA tracks VPN connections. The user “cmdLabs\bbaskin” was accessed via the IP address of 159.134.100.100 on 2 April, 2011, an IP that was traced back to Ireland. A few hours later the same account was accessed from an IP address in Austria.
Apr 2 21:53:37 192.168.1.1 Apr 02 2011 21: 53:08: %ASA-6-302013: Built outbound TCP connection 7823 for inside:10.10.10.50/389 (10.10.10.50/389) to NP Identity Ifc:192.168.1.1/1047 (192.168.1.1/1047) Apr 2 21:53:37 192.168.1.1 Apr 02 2011 21: 53:08: %ASA-6-104: AAA user authentication Successful : server = 10.10.10.50 : user = cmdLabs\bbaskin Apr 2 21:53:37 192.168.1.1 Apr 02 2011 21: 53:08: %ASA-6-113009: AAA retrieved default group policy (DfltGrpPolicy) for user = cmdLabs\bbaskin Apr 2 21:53:37 192.168.1.1 Apr 02 2011 21: 53:08: %ASA-6-113008: AAA transaction status ACCEPT : user = cmdLabs\bbaskin Apr 2 21:53:37 192.168.1.1 Apr 02 2011 21: 53:08: %ASA-6-734001: DAP: User cmdLabs\bbaskin, Addr 159.134.100.100, Connection Clientless: The following DAP records were selected for this connection: DfltAccessPolicy
For this small set of data it is trivial to query each IP address to determine its country of origin, netblock owner, and other details that would highlight unauthorized access. The problem arises when you have hundreds of thousands of such transactions in your daily log files.
