Last Updated: 2011-08-27 00:23:09 UTC
by Johannes Ullrich (Version: 1)
As we are looking at hurricane Irene taking aim at major population and technology centers on the east coast, here a couple of tech tips:
- Cell phone batteries last longer if you turn off non essential services like 3G, bluetooth, wifi.
- keep a hard copy of important phone numbers handy
- make sure all batteries are charged (including spare batteries you may have)
- electricity and water don't mix. If there is a threat of flooding, you may want to turn off the main breaker of your house (not if it is outside and it is wet / raining)
- hurricanes tend to come along with power outages. If you experience a power outage, disconnect major appliances, in particular sensitive ones like computers. During the recovery phase, irregular power and power spikes are likely (you may want to flip the main breaker)
- power suggest caused by lightning can travel over network cable. Unplug networks, in particular cable/DSL modems or other devices that connect to the "outside"
- in most cases, you will be safer at home in your house then on the road once the storm started. If you want to get out, get out now before it is too late
- to contact others, use SMS vs. voice calls. Most cell phone networks will deal with SMS much better then voice
The Red Cross is operating a site that you can use to leave brief "safe and well" messages : redcross.org/safeandwell . Twitter and Facebook can also be handy to leave quick messages for friends telling them that you are fine.
Security issues and Scams:
- if you evacuate your home, consider taking hard drives with other valuables (but they are not always easy to remove)
- frequently, the need arises to make quick system configuration changes to mitigate the impact of a location that is down. Document them carefully even if you appreciate normal change control.
- compromised social networking accounts could be used to send fake pleas for help (and money)
- only donate to reputable organizations that you know and trust. Don't donate to organizations you never heard about
- disaster movies and pictures are likely going to be used to spread malware
We will move this to a "disaster recovery" section that we are about to built. Let me know if you have additional tips. Also: What is in your "jump bag" of stuff that you would take with you?
Last Updated: 2011-08-26 00:11:28 UTC
by Daniel Wesemann (Version: 1)
Recently, while conducting an audit at a financial services company, I decided to verify their claim that their "desktop build is standardized" and "no other devices are on the network". The network team provided access to a SPAN port on their Internet uplink, where I attached my pen-test workstation to take a look.
$sudo ngrep -qt -W single -s1514 -d eth0 -P~ 'User-Agent:' 'port 80'
"ngrep" works like grep, but on network traffic. Thus, the above command digs through everything on port 80 (http) that the span port provides, and searches for the string "User-Agent:", which commonly contains the "signature" of the web client making the access. A little bit of cleanup was needed to make the output usable:
| sed 's/.*User-Agent/User-Agent/' | sed 's/~.*//' | sed '/^$/d'
This takes care of empty lines, and throws out everything that isn't part of the User-Agent: string. Collect the output into a file for a while, and then tally:
$cat output.txt | sort | uniq -c | sort -rn
And lookie, we ended up with about 80 distinct user agents. In only five minutes of traffic. Well, so far for "standardized desktop build" and "nothing else on the network". Among the user agent strings seen were
User-Agent: Mozilla/4.0 (compatible; Lotus-Notes/6.0; Windows-NT)
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1;.NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; .NET4.0C; .NET4.0E)
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:18.104.22.168) Gecko/20110303 Firefox/3.6.15 (.NET CLR 3.5.30729)
Hmm, peculiar, some users are surfing with IE7 on Windows XP, while others are using an oooold version of Lotus Notes, and again others are using a vulnerable version of Firefox ??
User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)
A couple of mobile devices ... with what looks like a Windows7/IE9 system thrown in for good measure. The mobile devices turned out to be most interesting, because unless there is a WiFi gateway hooked into the corporate LAN, these devices usually surf via the mobile phone network, and shouldn't show up in the company's outbound Internet traffic. Guess what we found a couple minutes later ...: a little unauthorized wireless network extension, using WEP and the company name as SSID. Duh...!
And, last but not least, we found some odd ducks that certainly warranted a closer look ..:
User-Agent: curl/7.8.1 (sparc-sun-solaris2.6) libcurl 7.9.6 (OpenSSL 0.9.6c)
User-Agent: Mozilla/4.0 (banzai)
Moral of the story: While your IDS probably alerts on "unusual" User Agent strings, it might nonetheless be a good idea to check out the full set of client applications that you have communicating with the Internet. The "User-Agent" string isn't failsafe, but it's a good start. You never know, you might just uncover a Secret (User) Agent who is busy squirreling away your data.
If you have other clever ways of auditing the user agent strings on your perimeter, please share in the comments below!