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CVE-2019-1019: Bypass SMB singing for unpatched machines #635

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merged 1 commit into from
Jun 13, 2019

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msimakov
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https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1019

Bypassing SMB singing by removing the target in NTLMSSP_CHALLENGE messages

@asolino
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asolino commented Jun 13, 2019

Hey @msimakov

Thanks for the PR.. Was very much looking forward for you to add your discoveries ;). Clever addition to the previous one (CVE-2015-0005), congrats.

I'll be testing it today. Windows SMB Clients still not working? (throwing INVALID_PARAMETER on your side?)

@msimakov
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Hi @asolino

Thanks, glad to contribute ;) Let me know if you run into any issues.
Windows SMB Clients still not working, they respond with a TCP RST and re-negotiate the SMB connection.

@asolino
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asolino commented Jun 13, 2019

Having some problems making it work @msimakov
Running it this way:

ntlmrelayx.py -machine-account FREEFLY.NET/machine\$ -machine-hashes LM:NT -domain FREEFLY.NET -t target -debug -remove-target -smb2support

I'm adding some comments in your code

res = NTLMAuthChallengeResponse()
res.fromString(authenticateMessageBlob)

new_auth_blob = hexlify(authenticateMessageBlob)[0:144] + b'00000000000000000000000000000000' + hexlify(authenticateMessageBlob)[176:]
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This just doesn't sound right. Are you trying to clear the previous MIC in order to calculate the HMAC_MD5 or something else?

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I'm clearing the previous MIC in order to calculate the new one (take a look at the next line - the relay_MIC)

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hi @msimakov , i am trying to use the script by myself and i am getting some errors. Basically i can see that i am able to retrieve the session key, but for some reason i cannot connect, i am using the following command just like @asolino said to use it in order to perform some tests.
by looking at wireshark on the relay endpoint i can see that, everything goes just like the article you published, but at the last message ( the one wit the new mic) i am getting Error:STATUS_INVALID_PARAMETER and the final login is failing.
Any ideas?

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Hi @zur250. Make sure to run the updated version, the file has been updated after this commit

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Thanks @msimakov for the quick answer. i am runnig Impacket v0.9.21-dev, is it the version you are talking about?

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Hey @zur250. I think you have a mix of impacket versions installed. What is the banner you get when you run ntlmrelayx.py? (at the very beginning of its execution)

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@asolino hi, the banner is the following :
Impacket v0.9.21-dev - Copyright 2019 SecureAuth Corporation

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Ok.. so it has nothing to do with this commit commit we're writing in. It has to be a separate issue.

@asolino asolino merged commit 5257b9d into fortra:master Jun 13, 2019
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asolino commented Jun 13, 2019

Merged! Thanks a lot @msimakov !

For those testing this, it can be run this way:

./ntlmrelayx.py -machine-account domain/machineAccountName -machine-hashes LM:NT -domain DOMAIN -t targetIP -remove-target -smb2support

Don't forget it will work only for victims connecting thru HTTP (SMB to SMB not yet supported)

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3 participants