January 2003 - openSUSE Security - openSUSE Mailing Lists

RE: [suse-security] Login as root unsecure?!
by Ronny Martin 22 Jan '03

22 Jan '03

> * Mario Ohnewald wrote on Mon, Jan 20, 2003 at 09:41 +0100: > > > If you login as root someone can get your passwd and login > > > and get full controll over your server. > > I do not understand why that. > > I meat why login as a user and THEN do su is more secure than > > login in directly as root. > > I don't see why this should be better. Well, and if someone get's > a user account on the server, there are more chances to get root > by some missed local exploit or such. > Think the main issue for not allowing direct root logins is administration. If something goes wrong on a server where multiple people have root access, you can check who su'ed at the time something happened. It doesn't need to be only bad intentions, but everyone makes mistakes or easy to know who to ask what could have been changed when something suddenly fails. Disallowing root access also decreases the habbit of doing everything as root as well

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RE: [suse-security] Login as root unsecure?!
by Mario Ohnewald 22 Jan '03

22 Jan '03

Hi, > From: Philippe Vogel [mailto:filiaap@freenet.de] > Sent: Montag, 20. Januar 2003 09:36 > > > Hello! > > I keep reading that it is unsecure to log in directly as > root. To use su > > should be the choise. > > But why?? > > Suppose of the worst case somebody hijacking your connection > and grabbing > data of your ssh-connection. via DNS-Spoofing for example. Well, then it won´t help to log in with a user and then su to root. > If you login as root someone can get your passwd and login > and get full > controll over your server. > The next thing can be a brute-force attack (login as root and > look passwords > from e.g. a database). > That's why it's insecure. > > Locally logins are insecure in the way inexperianced users > may alter the > system by misconfiguring or deleting needed files. > This is not real insecure - it is your own fault. > If you use root you really should know what you are doing. Of course. > If not have fun and reinstall everything! > I meat why login as a user and THEN do su is more secure than login in directly as root. Cheers, Mario

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OT pop3 help
by webmaster 21 Jan '03

21 Jan '03

Hello, I know it is OT but hoping one can advice me on: strange thing with popper that gives Timeout only at one of the accounts on a Lan W2 machine that connects to SuSe 7.1. Outlook settings as well as Linux are all alike - this account worked flowless as the rest does, and suddenly the Outlook err 0x8004210A says the Pop does not answer. I cannot finde any trace of anything. Pine collects emails from that account - Outlook collects all, except that one. /var/spool/mail/account are all oke etc/inetd.conf oke telnet localhost 110 - oke pop working Password changed & checked Any ideas? Thank you> Antal ++++++++++++++++++++ Kreorg Oktatóközpont Hunyadi tér 8, Budapest 1067 ++++++++++++++++++++ kreorg(a)kreorg.hu http://www.kreorg.hu ++++++++++++++++++++ Grid - Erő a változáshoz.

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SuSE Security Announcement: susehelp (SuSE-SA:2003:005)
by Sebastian Krahmer 20 Jan '03

20 Jan '03

-----BEGIN PGP SIGNED MESSAGE----- ______________________________________________________________________________ SuSE Security Announcement Package: susehelp Announcement-ID: SuSE-SA:2003:005 Date: Mon Jan 20 14:00:00 CET 2003 Affected products: SuSE Linux 8.1, SuSE Linux Enterprise Server 8, SuSE Linux Office Server, SuSE Linux Openexchange Server 4 Vulnerability Type: remote command execution Severity (1-10): 5 SuSE default package: no Cross References: - Content of this advisory: 1) security vulnerability resolved: Remote command execution due to broken filtering of shell metacharacters in CGI queries. problem description, discussion, solution and upgrade information 2) pending vulnerabilities, solutions, workarounds: mod_php4 3) standard appendix (further information) ______________________________________________________________________________ 1) problem description, brief discussion, solution, upgrade information During a code review of the susehelp package the SuSE Security Team recognized that the security checks done by the susehelp CGI scripts are insufficient. Remote attackers can insert certain characters in CGI queries to the susehelp system tricking it into executing arbitrary code as the "wwwrun" user. Please note that this is only a vulnerability if you have a web server running and configured to allow access to the susehelp system by remote sites. We nevertheless recommend an update of this package. As a temporary workaround you may un-install the susehelp package by issuing the following command as root: rpm -e --nodeps susehelp Please download the update package for your distribution and verify its integrity by the methods listed in section 3) of this announcement. Then, install the package using the command "rpm -Fhv file.rpm" to apply the update. Our maintenance customers are being notified individually. The packages are being offered to install from the maintenance web. SuSE-8.1: ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/noarch/susehelp-2002.09.05-… 6dde3d487385fd6a935643b1a0d92b86 ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/noarch/susehelp-SLOD-2002.0… cd91f786f056518a11192b1ce9597783 ______________________________________________________________________________ 2) Pending vulnerabilities in SuSE Distributions and Workarounds: - mod_php4 A buffer overflow in the wordwrap() function has been reported. New packages will be prepared and should be availble soon on our ftp servers. ______________________________________________________________________________ 3) standard appendix: authenticity verification, additional information - Package authenticity verification: SuSE update packages are available on many mirror ftp servers all over the world. While this service is being considered valuable and important to the free and open source software community, many users wish to be sure about the origin of the package and its content before installing the package. There are two verification methods that can be used independently from each other to prove the authenticity of a downloaded file or rpm package: 1) md5sums as provided in the (cryptographically signed) announcement. 2) using the internal gpg signatures of the rpm package. 1) execute the command md5sum <name-of-the-file.rpm> after you downloaded the file from a SuSE ftp server or its mirrors. Then, compare the resulting md5sum with the one that is listed in the announcement. Since the announcement containing the checksums is cryptographically signed (usually using the key security(a)suse.de), the checksums show proof of the authenticity of the package. We disrecommend to subscribe to security lists which cause the email message containing the announcement to be modified so that the signature does not match after transport through the mailing list software. Downsides: You must be able to verify the authenticity of the announcement in the first place. If RPM packages are being rebuilt and a new version of a package is published on the ftp server, all md5 sums for the files are useless. 2) rpm package signatures provide an easy way to verify the authenticity of an rpm package. Use the command rpm -v --checksig <file.rpm> to verify the signature of the package, where <file.rpm> is the filename of the rpm package that you have downloaded. Of course, package authenticity verification can only target an un-installed rpm package file. Prerequisites: a) gpg is installed b) The package is signed using a certain key. The public part of this key must be installed by the gpg program in the directory ~/.gnupg/ under the user's home directory who performs the signature verification (usually root). You can import the key that is used by SuSE in rpm packages for SuSE Linux by saving this announcement to a file ("announcement.txt") and running the command (do "su -" to be root): gpg --batch; gpg < announcement.txt | gpg --import SuSE Linux distributions version 7.1 and thereafter install the key "build(a)suse.de" upon installation or upgrade, provided that the package gpg is installed. The file containing the public key is placed at the top-level directory of the first CD (pubring.gpg) and at ftp://ftp.suse.com/pub/suse/pubring.gpg-build.suse.de . - SuSE runs two security mailing lists to which any interested party may subscribe: suse-security(a)suse.com - general/linux/SuSE security discussion. All SuSE security announcements are sent to this list. To subscribe, send an email to <suse-security-subscribe(a)suse.com>. suse-security-announce(a)suse.com - SuSE's announce-only mailing list. Only SuSE's security announcements are sent to this list. To subscribe, send an email to <suse-security-announce-subscribe(a)suse.com>. For general information or the frequently asked questions (faq) send mail to: <suse-security-info(a)suse.com> or <suse-security-faq(a)suse.com> respectively. ===================================================================== SuSE's security contact is <security(a)suse.com> or <security(a)suse.de>. The <security(a)suse.de> public key is listed below. ===================================================================== ______________________________________________________________________________ The information in this advisory may be distributed or reproduced, provided that the advisory is not modified in any way. In particular, it is desired that the clear-text signature shows proof of the authenticity of the text. SuSE Linux AG makes no warranties of any kind whatsoever with respect to the information contained in this security advisory. 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RE: [suse-security] restricting ssh
by Punt, Ryan 20 Jan '03

20 Jan '03

> i would like to enable ssh for just two users of all > users of my computer. > Do you know where i could find an howto to do that ?? Guillaume: You're looking for the "AllowUsers" directive. See http://216.239.53.100/search?q=cache:ex37_lQD-6YC:www.onlamp.com/pub/a/bsd/2 002/11/28/FreeBSD_Basics.html%3Fpage%3Dlast+ssh+AllowUsers&hl=en&ie=UTF-8 (Sorry about the long URL). FYI, the "AllowGroups" directive might come in handy too. ~rlp

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restricting ssh
by Guillaume Devoyon 20 Jan '03

20 Jan '03

Hello, i would like to enable ssh for just two users of all users of my computer. Do you know where i could find an howto to do that ?? Guillaume

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RE: [suse-security] SuSEfirewall2 on multiple servers but no "firewall"
by Peer Stefan 20 Jan '03

20 Jan '03

Hi Peter > From: Peter Romianowski [mailto:antarapero@gmx.de] > Hi, > > I will have to install several servers all connected > only with a switch and no standalone Firewall-Server. > Looks like this: > > ( | ISP ROUTER | ) > | > | > | SWITCH | > | > ----------------------- ... > | | > | SERVER #1 | | SERVER #2 | ... > > I plan to install SuSEfirewall2 on every server and blocking > all traffic from other IP-Adresses than my own range. All servers > do only have public IP-Adresses. My Question: I would use a setup like this: (|ISP-Router|) | | (|Firewall|) | ---------(|SWITCH|)--------------- ... | | | (|Server 1|)(|Server 2|)(|Server 3|) ... > 1. Is that feasable? Theoretically yes, though I think portforwarding on the firewall is a much more secure way to handle incomming requests. > 2. Is that total nuts? No, just nuts ;-) Nah, couldn't resist. It's possible, though it's much harder to administer (if you have something like 20 Servers ;). > 3. Has running the firewall on every server a hard performance > impact? I run a firewall on every server I use without recognizable performance-loss. > 4. If 2.) is true, how would I set up a failsafe setup with > 2 SuSEfirewall2 Servers? What do you mean by failsafe setup? Do you use clusters? If so, do yourself a favor and use one firewall in front of your cluster. You can even use something like heartbeat to create a firewall-cluster (for failover purpose only). It's very easy to set this up. > Many thanks for digging into my humble mind :) You're welcome. > Peter regards, Stefan

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Re: [suse-security] OT: literature
by GentooRulez 20 Jan '03

20 Jan '03

As you wrote: OT ANYWAY -EAT THIS http://www-106.ibm.com/developerworks/library/l-bash.html there are other tutorials in ibm developer network, too Michael

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Redirection on SuSE-FW2, SuSE 8.0
by Ingo Doerrie 20 Jan '03

20 Jan '03

Hello! I got some problems with my SuSE 8.0 box running as dialup router (DSL) and proxy server. I want all my HTTP-traffic to go thru the Squid installed onto the box. To reach this goal I configured the proxy that does a good job if I set my browsers to use it. To avoid direct connections to the internet I set a FW_REDIRECT option in the configuration file of FW2 telling the Firewall to redirect all traffic coming in from the internal net on port 80 to the local port 3128 on what Squid is listening. The effect is that all direct connections to the internet are cut off (HTTP) and I get an error message from the Proxy that he is not able to reach the URL '\'. So, something gets lost using a redirector. What did I do wrong? How can I fix this bug? Thank you for your help in advance! -- Freundliche Grüße kind regards Ingo

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Login as root unsecure?!
by Mario Ohnewald 20 Jan '03

20 Jan '03

Hello! I keep reading that it is unsecure to log in directly as root. To use su should be the choise. But why?? Cheers Mario

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