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Showing posts with label Tshark. Show all posts
Showing posts with label Tshark. Show all posts

Tuesday, October 29, 2013

Network Forensics with Tshark: Psexec intrusion

I love Tshark for network forensics; I think the command line version of Wireshark can be really efficient if it used wisely to detect a big amount of anomalies/attacks in our network. Let's see the next case.

The internal server (192.168.1.130/24) of a certain organization has been compromised several times. The fact that the server is not accessible from the outside led us to think that an internal user had also been compromised, and the attacker was doing "pivoting" from that machine to the server. Another option was that an infected USB had been the root of the problem. However, after checking that the firewall did not filter the traffic DMZ ---> Internal Network, we could confirm that this was the origin of the intrusion. The web server (192.168.20.1/24) in the DMZ was compromised, and from here the attacker could access the internal LAN using the Administrator account. To do this the attacker used Mimikatz to get the credentials of that machine and then ran Psexec against the internal server with the Administrator account.

Thursday, September 12, 2013

Passive DNS with Tshark

Passive DNS is a nice monitoring technique to get the relationships of domains and IP addresses. With this information we can identify fast-flux botnets that constantly update DNS with very low TTL values, know where a domain name pointed to in the past, what domain names are on a given IP and so on.  

I usually use pdnstool to query about a specific domain or IP as it allows me to choose multiple passive DNS databases (DNSParse, ISC, BFK,  CERTEE). In the next example I query the BFK database to get information about spotsmalldor.com.

root@mordor:~# pdnstool -b spotssmalldor.com
source response_time query answer rrtype ttl firstseen lastseen count
BFK 0.707719847 spotssmalldor.com 37.153.192.72 A
BFK 0.707719847 spotssmalldor.com 42.121.84.12 A
BFK 0.707719847 spotssmalldor.com 95.87.1.19 A
BFK 0.707719847 spotssmalldor.com 111.93.115.216 A
BFK 0.707719847 spotssmalldor.com 140.116.72.75 A
BFK 0.707719847 spotssmalldor.com 223.30.27.251 A
BFK 0.707719847 spotssmalldor.com ns1.treesmustdownload.su NS
BFK 0.707719847 spotssmalldor.com ns1.checklistsseesmics.su NS
BFK 0.707719847 spotssmalldor.com ns1.boardsxmeta.com NS
BFK 0.707719847 spotssmalldor.com ns1.higherpricedan.com NS