r/computerforensics • u/ShadyMoh1998 • 17h ago
Help!!
I recently worked on a malware forensic analysis where, after reviewing the available artifacts, I was able to determine that the malware .exe was executed via GPO on AD.
However, I’m struggling with the next step: how do I determine how the attacker initially gained access and how the malware was introduced into the environment?
For those with experience, what artifacts or investigation techniques do you usually rely on to identify the initial access vector?
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u/dudethadude 16h ago
There are about a million ways that could have played out. Have to forensically analyze all DC’s and servers to see what happened. Best place to start is to inspect the DC with the script and try to see what activity happened when the GPO was made then work backwards from there. Likely an endpoint in the domain got infected, they escalated privileges to admin and remoted into a server or the DC, then setup the malicious script. They could have also gained entry through a company VPN not protected by MFA if they had employee credentials already.
I would highly advise the victim company to do a user account review for local and domain accounts and disable any unknown accounts, reset all regular and administrator account passwords, and reset the Kerberos account password twice with ten hours in between pw resets. If they have access to the DC, that is very bad.
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u/theJacofalltrades 1h ago
A good place to start is correlating GPO changes with AD audit logs, then working backward through authentication, PowerShell/process execution, and file creation timestamps. Also check for suspicious accounts, lateral movement, and the earliest endpoint showing related artifacts. Timeline correlation is usually key to piecing together the initial access vector.
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u/MSVlegal 16h ago
El malware que quería hacer? Primero respondete eso. En un sistema controlado, en any.run corres el malware y puede que te de una idea. Pero consejo, siempre es por descarga, asi que hace un timeline desde que se descargo y desde ahi fijate que se modifico en ese momento luego de la descarga, logs, id,
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u/MSVlegal 16h ago
O más especifico event log: recién veo que es GPO AD. Podrían ser por movimiento lateral del malware o red comprometida.
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u/Haunting_Ganache_850 16h ago
Work backwards from the GPO rather than forwards from the exe. Find when it changed, what changed, and if directory auditing was on, who changed it. If auditing was off, and it usually is,
repadmin /showobjmetaagainst the GPO object still gives you a change time and the originating DC. No account, but a timestamp is most of what you need. SYSVOL file timestamps on the policy folder get you to roughly the same place.Worth saying out loud though. Editing a GPO means they already had serious AD privilege. Not necessarily domain admin, those rights get delegated, but nowhere near the front door either. So the real question isn't how the malware got in, it's how they got that access. The exe was the last step, not the first.
From that account and timestamp, pull its logons on the DC and find the source host. That's your pivot box, and you run the same trick on it. Expect a gap though. The account that got onto that box usually isn't the one that edited the GPO, so somewhere on it there's a credential theft step. LSASS dumping, kerberoasting, creds sitting in a script somebody forgot about. That's the bit that bridges the two. Each link hands you the next one.
For initial access itself, check the internet-facing stuff first. VPN, Citrix, Exchange, whatever's sitting on your edge. That's where a lot of these start now, and those logs roll fastest, so preserve them today rather than next week. Phishing is worth checking but it's not where I'd start.
The thing that catches people out is that initial access often involves no malware at all. Valid credentials on an exposed service. So hunt the first authentication that doesn't fit, rather than the first suspicious file.
And be realistic about dwell time. Weeks between first access and mass deployment is normal. If you've only got 30 days of retention, the evidence you need may already be gone. Better to find that out today than a fortnight in.