Security Basics mailing list archives
Re: McAfee Anti Virus V4.5.1 SP1
From: Jimi Thompson <jimit () myrealbox com>
Date: Fri, 28 Nov 2003 11:02:23 -0600
If I recall correctly, this version of McAfee can be configured to scan any hard drives as well as memory periodically. I know that we typically set the servers to scan at 4am (to avoid our back up process) and desktops to scan at midnight every day just to catch this type of thing. We also set the virus definitions to self update at 11pm every day. In addtion, we deployed the ePolicy Orchestrator so that we can manage the anti virus stuff from a single console. You do NOT need the the ePolicy Orchestrator to make the configuration for the above, but if you don't have then it means going out and physically touching all the machines to make sure that they are set correctly. It also becomes slightly problematic to keep the user from changing settings or disabling the scanning completely.
The next thing to deal with is going to be your patch management process. Obviously, something has gone quite wrong with it. You are going to have to find out why the machines were vulnerable to this. Did the patch not apply properly? Did they not get the patch? There are some questions here that really need to be answered.
Third, how did this thing get on your network in the first place? Why didn't your IDS pick the intital infection?
Good Luck, Jimi Pour, Matthew wrote:
To add a bit more to this, Nachi tends to write itself in memory (DLLHOST.EXE), so VirusScan 4.5.1 will not pick this up. Durring the on-demand scan, it finds the two culprit files and deletes them. VirusScan 7.0 has a memory scanner, so as long as the definition file is current, it will catch Nachi before it writes to the drive. However, as stated below, it does not beat patching the system or disabling DCOM. -Matt -----Original Message----- From: Robert Slade, Threat Response Manager To: mjcarter () ihug co nz Cc: security-basics () securityfocus com; focus-virus () securityfocus com Sent: 11/27/2003 2:37 PM Subject: Re: McAfee Anti Virus V4.5.1 SP1We have had 3 or 4 machines come up infected with Nachi today but theonaccess scanner didn't pick it up. Carrying out a full system scan did pick it up.Not terribly surprising. First of all, Nachi (and a great many others of its ilk) is a worm, acting specifically by making an attack on a vulnerability in an application or an operating system. In this case, it is, as you note, making RPCcalls. (Turning off DCOM with something like dcomcnfg will prevent the attackfrom succeeding, and shouldn't create any problems unless you are using an MS Exchange mail server.) Nachi creates the files you note, but it does not necessarily read them. Generally on-access scanners shortcut scanning (in order to improve performance) and therefore the scanner will probably never scan the files. The full scan, as you noted, does. (In addition, on-access or other "automatic" scanners are always much less effective and accurate at detection in comparision to the base manual versions.)Anyway... I'm trying to figure out why McAfee on access scanner isn't picking these files up but the full system scan is. There is no difference in the setup we have between on access or full scan.Hope this explains matters.
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Current thread:
- RE: McAfee Anti Virus V4.5.1 SP1 Eric Coulombe (Nov 28)
- <Possible follow-ups>
- Re: McAfee Anti Virus V4.5.1 SP1 Robert Slade, Threat Response Manager (Nov 28)
- Re: McAfee Anti Virus V4.5.1 SP1 Nick FitzGerald (Nov 28)
- RE: McAfee Anti Virus V4.5.1 SP1 Pour, Matthew (Nov 28)
- RE: McAfee Anti Virus V4.5.1 SP1 Pour, Matthew (Nov 28)
- Re: McAfee Anti Virus V4.5.1 SP1 Jimi Thompson (Nov 28)
- McAfee Anti Virus V4.5.1 SP1 Mike (Nov 28)
- Re: McAfee Anti Virus V4.5.1 SP1 Lou (Nov 28)