Finding hidden gems (easter eggs) in your logs (packet challenge!)

Published: 2008-03-23
Last Updated: 2008-03-23 20:23:58 UTC
by Johannes Ullrich (Version: 1)
0 comment(s)
Happy easter everyone who happens to be celebrating that holiday. At least here in Jacksonville FL, its a beautiful warm day. If its cold and miserable were you are: what a great day to go hunting for easter eggs in your logs! This is prompted by a post from a reader who sent in the "sludge" as he called it: A quick summary of reports he typically sends to DShield. Did I mention lately that y'all should be sending your logs to DShield?

Anyway. He used some nice shell scripting to summarize his logs. I like this technique and frequently use it myself. You should all become familiar with the little gems hidden in your respective shells. Even Windows got something to offer in that department (search for past "Windows Shell Kung-Fu" posts by Ed for example).

In my opinion, the goal is to find "unusual" log entries. I am typically less interested in the thousands of SQL slammer infected hosts hitting me each day. And yes, they still exist :-(. What I am interested in are the "one off" hits.

Here a quick shell command I like to summarize my iptables firewall logs:

sed 's/.*SRC=//' < /var/log/firewall | sed 's/ .*DPT//' | sort | uniq -c | sort -n

Its not exactly pretty... but well, it works.

Browsing through the output, this one entry caught my attention:

1 192.228.79.200=27639 LEN=541

Its UDP (otherwise you would see more details about flags and such given the command sequence I used), it got payload, and it is sent to an odd port

Next lets look at the full line:

grep 27639 /var/log/firewall
Mar 23 18:17:20 defianta kernel: filter: cable-dmz IN=eth2 OUT=eth0
   SRC=192.228.79.200 DST=10.0.0.2 LEN=561 TOS=0x00 
   PREC=0x20 TTL=43 ID=0 DF 
   PROTO=UDP SPT=53 DPT=27639 LEN=541 

hm. from port 53. So maybe just a DNS response? But why did it get blocked? Now it is helpful to have full packet captures. I tend to capture each packet entering and leaving my network. Its not a huge amount of data (few gbytes per day), so I can keep about a month worth.

tcpdump -r snort.log.1206295201 -nn host 192.228.79.200
reading from file snort.log.1206295201, link-type EN10MB (Ethernet)
18:17:20.655144 IP 192.228.79.200.53 > 70.91.145.9.27639:  64286- 0/13/16 (533)

Interesting. The only thing I see is a DNS reply, with no answers, but plenty of authority records. Its also rather large. Unless edns0 is used, DNS replies should stick to 512 Bytes!

off I am into packet land to figure out what this was exactly about. More to come soon... it will involve an AAAA record (hehe... what a cliffhanger)

If you want to take a look, see http://isc.sans.org/odddns for the packet. (no... finding the packet was not staged. That's exactly how I got it.)

Johannes B. Ullrich, Ph.D.
jullrich at sans.org
Keywords: challenge dns packets
0 comment(s)

Comments

What's this all about ..?
password reveal .
<a hreaf="https://technolytical.com/">the social network</a> is described as follows because they respect your privacy and keep your data secure:

<a hreaf="https://technolytical.com/">the social network</a> is described as follows because they respect your privacy and keep your data secure. The social networks are not interested in collecting data about you. They don't care about what you're doing, or what you like. They don't want to know who you talk to, or where you go.

<a hreaf="https://technolytical.com/">the social network</a> is not interested in collecting data about you. They don't care about what you're doing, or what you like. They don't want to know who you talk to, or where you go. The social networks only collect the minimum amount of information required for the service that they provide. Your personal information is kept private, and is never shared with other companies without your permission
https://thehomestore.com.pk/
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> public bathroom near me</a>
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> nearest public toilet to me</a>
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> public bathroom near me</a>
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> public bathroom near me</a>
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> nearest public toilet to me</a>
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> public bathroom near me</a>
https://defineprogramming.com/
https://defineprogramming.com/
Enter comment here... a fake TeamViewer page, and that page led to a different type of malware. This week's infection involved a downloaded JavaScript (.js) file that led to Microsoft Installer packages (.msi files) containing other script that used free or open source programs.
distribute malware. Even if the URL listed on the ad shows a legitimate website, subsequent ad traffic can easily lead to a fake page. Different types of malware are distributed in this manner. I've seen IcedID (Bokbot), Gozi/ISFB, and various information stealers distributed through fake software websites that were provided through Google ad traffic. I submitted malicious files from this example to VirusTotal and found a low rate of detection, with some files not showing as malware at all. Additionally, domains associated with this infection frequently change. That might make it hard to detect.
https://clickercounter.org/
Enter corthrthmment here...

Diary Archives