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Date: Thu, 11 Jun 2020 19:26:19 +0200
From: Mikhail Morfikov <mmorfikov@...il.com>
To: lkrg-users@...ts.openwall.com
Subject: Re: [p_lkrg] <Exploit Detection> Someone is trying to
execute file: [//////////////]
On 11/06/2020 19:01, Adam Zabrocki wrote:
> On Wed, Jun 10, 2020 at 11:04:35PM +0200, Mikhail Morfikov wrote:
>> I know that the LKRG's UMH blocking feature is supposed to block execution of
>> files from paths which aren't whitelisted (when lkrg.umh_validate is set to
>> "1"). But what file is it actually blocking when I get bunch of the following
>> messages in the log?
>>
>> kernel: [p_lkrg] <Exploit Detection> !!! BLOCKING UMH !!!
>> kernel: [p_lkrg] <Exploit Detection> Someone is trying to execute file: [//////////////]
>> kernel: [p_lkrg] <Exploit Detection> --- . ---
>
> When LKRG blocks execution it overwrites original path with slash chars. If you
> see that in the log, it means someone is executing something through UMH which
> was already previoussly blocked. You can't restore what was blocked.
So how to determine what path would that be, because I don't really know what
causes it, and if I had the file name, then it would be easier to figure it out
what's going on.
>>
>> I've seen something like the following:
>>
>> kernel: [p_lkrg] <Exploit Detection> !!! BLOCKING UMH !!!
>> kernel: [p_lkrg] <Exploit Detection> Someone is trying to execute file: [/sbin/modprobe]
>> kernel: [p_lkrg] <Exploit Detection> --- . ---
>>
>> And in this case the name is displayed, so there's no problem here, but what
>> about the "slasher" file?
>>
>> Also I have question concerning the feature itself -- will it be possible to
>> define some custom paths to be included in the whitelist via sysctl?
>>
>
> For now, we only support hardcoded whitelist. You can easily add your own path
> to the LKRG source code. Also list is evolving and we adding / removing some
> entires.
>
> Btw. modprobe is whitelisted.
I know, but I've set it to block UMH altogether for testing purposes.
>
> Thanks,
> Adam
>
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