Re: My Linux server got hacked last night -- please help!

From: Darren Tucker (dtucker_at_dodgy.net.au)
Date: 11/30/04

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    Date: 30 Nov 2004 09:50:21 GMT
    
    

    In article <24d1fc75.0411291116.57cfad5b@posting.google.com>,
    sarah chang <sarahd00d@yahoo.co.uk> wrote:
    >It looks as though my Linux server (running RedHat Fedora Core 3) was
    >hacked last night.
    >
    >I see the following files in my /lib directory (note modification
    >times, permissions and sizes)
    >
    >?---rwS--T 2200 4249291143 4170711954 4253155062 Dec 20 1974
    >libc-2.3.3.so
    [...]

    This looks to me like a failing disk or filesystem corruption rather
    than, er, enemy action.

    >Nov 29 04:55:02 andromeda sshd[32300]: Invalid user admin from
    >::ffff:210.212.85.11

    These look like the characteristic failures from the password-guessing
    ssh worm that's going around (it was mentioned on full-disclosure
    a while back). I've captured some of these attempts and the look to
    me like vanilla password auth attempts. There appears to be at least
    2 variants, the most prolific tries user/password pairs of root/root,
    admin/admins, user/user and test/test.

    The fact that it apparently has a non-zero success rate makes me wonder
    sometimes... I mean if your internet-accessible box has a root password
    of "root" then connecting with strong crypto isn't going to help much.

    >I'd appreciate any advice on
    >1) How to cleanse my system

    Either way, you can't trust what's on the disk. Perform a clean install,
    preferably on a new disk and restore what you need from backup.

    >2) How to avoid this type of attack in future.

    Not enough info to comment.

    -- 
    Darren Tucker (dtucker at zip.com.au)
    GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
        Good judgement comes with experience. Unfortunately, the experience
    usually comes from bad judgement.
    

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