openSUSE Security April 2000

security@lists.opensuse.org

81 participants
100 discussions

SSH Authentication
by Joao Reis 18 Nov '02

18 Nov '02

Hi! I implemented a ssh conection from the outside to my intranet. This ssh requires a username and a password. In terms of security what is more secure: require authentication (username and password) or having the public key of each user that connects to our intranet in the authorized public key lists (in this case there is no need for username and password)? In the second case there is no need of authentication and only the users wich have the public keys in the list are allowed to enter in my intranet. This second solution is a good solution or that brings other security problems ? Thanks. -- Farewell. "Keep your friends close, but your enemies closer." "Do or do not. There is no try" - Yoda João Reis -------------------------------------------------------

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Re: is SuSE going to implement libsafe?
by marc＠suse.de 18 Feb '01

18 Feb '01

Hi, >I have just read an Bell Labs anouncement, that they are going to release >libsafe under GNU licence, and that some major Linux distros are going to >be using it. SuSE was not amongst them, why is that? I think that libsafe would >be a good echnacement against buffer overflow. > >Anouncement is on: >http://www.bell-labs.com/news/2000/april/20/1.html just because something new pops up please be careful with questions like "when will you implement it?" ;-) There are several questions to ask: a) is it STABLE and does it NOT affect the stability of other programs? b) does it bring additional security problems into the system? c) is the security protection effective? Well, of course the SuSE Security Team already reviewed libsafe. Here are the answers: a) unsure. it would have to be tested very intensive. this was not done yet. b) the code might have vulnerabilities, however the protection gained is higher even if a vulnerability would be present c) okay, now the tough part: libsafe is a dynamic library which is set in the environment which checks several dangerous functions, which can be a security problem. Because it is a dynamic library, it is NO protection against local attackers, just against remote attackers on network services. (if an attacker wants to attack a local suid file, he would just reset his library path environment). Next thing: it does not check for all known vulnerabilites. It even doesn't protect against all buffer overflows, It just protects against *some* overflows. those which happen because of insecure use of strcat/strcpy etc. summary: I can not remember a vulnerability in a network service for the last year which this tool would have prevented. Therefore: as long as this tool is not enhanced to also protect open/fopen calls against symlink/hardlink/pipe attacks, several more buffer overflow types, system/exec* function protection etc. it is not useful to use this tool. I would rather propose to use the secumod module which comes with SuSE Linux since 6.3 and maybe the secure-linux kernel patch from www.openwall.com - these two tools enhance your security. (and btw, install seccheck, hardensuse and firewals and use them - then your security is very high) Greets, Marc -- Marc Heuse, SuSE GmbH, Schanzaeckerstr. 10, 90443 Nuernberg E@mail: marc(a)suse.de Function: Security Support & Auditing "lynx -source http://www.suse.de/~marc/marc.pgp | pgp -fka" Key fingerprint = B5 07 B6 4E 9C EF 27 EE 16 D9 70 D4 87 B5 63 6C

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multi-services server securing
by Gediminas Grigas 16 Aug '00

16 Aug '00

Hello there, I feel erroneusly (?) secure after .host.denyed in.telnetd and in.sshd from everywhere except one pc, which is denying all exept keyboard. I belive that if i can keep hosts.deny and hosts.allow files safe, and from time to time patch most actual security holes i`ll be conditionaly safe. Em i wrong? Probably I do. I just cant imaginate how system can be cracked in lower stage, so that is my problem. I heard that inetd is very insecure, and some peoples using tcpd (or soundlike). I run harden_suse, but was forced to answer 8/10 to no, as my server should provide a lot of public services, and have world writible directories as well. And thats right - this script was developed not for systems like mine one. However i`ll run SuSE-firewall-3.0 script, to make my system even stronger. But thats all. I dont know what can i do else. I should keep folowing services open: httpd; smptd; pop3d; ftpd; snmpd; named; inetd; sshd; nscd. So if you know how to keep them at minimal risk, or know some holes at those, i would be very gratefull for any info and/or tips. I dont ask to do work for me - link to good manual would be nice too. By the way i have SuSE 6.3 (2.2.13). Thanks in advice. Sincerely Yours, Gediminas Grigas mailto:gedas@kryptis.lt

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Invisible X?
by Ragnar Beer 19 May '00

19 May '00

Howdy! I like to have as many as possible ports closed. Is it possible to configure X in a way that it's only "visible" for localhost/127.0.0.1 ? --Ragnar

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encryption
by jonathan 01 May '00

01 May '00

Hello security folks, what tools comes with 6.4 to encrypt my hard drive or partition? Since I have a cable modem connection, I am a little paranoid. I would like to encrypt my firewall system and the drive the holds our data on another system inside the firewall. Thanx

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Re: [suse-security] SuSE Security Announcement - aaa_base
by marc＠suse.de 30 Apr '00

30 Apr '00

Hi, the update rpm for 6.2 is wrong, so you can't use that one :-( There should be a 6.1 - use this when it becomes available. sorry, but the build for 6.1 and 6.2 failed. We will supply the missing/new/corrected rpm's asap. Greets, Marc > On Sat, 29 Apr 2000, you wrote: > >-----BEGIN PGP SIGNED MESSAGE----- > > > >______________________________________________________________________________ > > > > SuSE Security Announcement > > > > Package: aaabase < 2000.1.3 > > Date: Sat, 29 Apr 2000 14:03:28 GMT > > > > Affected SuSE versions: all > > Vulnerability Type: remove any local file(s) > > executing attacker supplied commands as non-root > > SuSE default package: yes > > Other affected systems: unknown > > > >______________________________________________________________________________ > > > >Please verify these md5 checksums of the updates before installing: > > > >369c48687807875e9b01f24b6e6bb061 ftp://ftp.suse.com/pub/suse/axp/update/6.3/a1/aaa_base-2000.1.3-0.alpha.rpm > >350cabc140a177dfa1909d356c982647 ftp://ftp.suse.com/pub/suse/i386/update/6.2/a1/aaa_base-99.9.8-0.i386.rpm > >1b0ccf6db229d6c45692588d826853b7 ftp://ftp.suse.com/pub/suse/i386/update/6.3/a1/aaa_base-2000.1.3-0.i386.rpm > >34ff11f9ffd877231fab6add4a1723dd ftp://ftp.suse.com/pub/suse/i386/update/6.4/a1/aaa_base-2000.4.27-1.i386.rpm > >______________________________________________________________________________ > > According to the announcement all SuSE versions are affected. But there are only > updates for 6.2, 6.3 and 6.4 > I am running SuSE 6.0. Which update should I use? > > regards, > Allard > -- Greets, Marc -- Marc Heuse, SuSE GmbH, Schanzaeckerstr. 10, 90443 Nuernberg E@mail: marc(a)suse.de Function: Security Support & Auditing "lynx -source http://www.suse.de/~marc/marc.pgp | pgp -fka" Key fingerprint = B5 07 B6 4E 9C EF 27 EE 16 D9 70 D4 87 B5 63 6C

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firewall
by Mitja 30 Apr '00

30 Apr '00

I tried to configuring firewall on standalone machine with modem connecting on Internet (mode is on tty0). I received next messages: Starting Firewall Initialization: (final run) ppp0: error fetching interface information: Device not found Warning: interface ppp0 is faulty. Ignore if it's not active yet (eg. [i]pp0) No interface active! exiting... SuSEfirwall: clearing rules now...done Failed services in runlevel2: firewall_final Thanks in avance, Mitja

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Re: [suse-security] SuSE Security Announcement - aaa_base (fwd)
by Volker Weinberg 29 Apr '00

29 Apr '00

Hallo! After updating a SuSE 6.3 box , /etc/passwd was no longer readable for g+o and I got the following output. No E-Mail was sent to root. root@glockner1:~ > rpm -Uvh aaa_base-2000.1.3-0.i386.rpm aaa_base ################################################## Updating etc/rc.config... Updating etc/passwd... Exception in ../SRC/parser.c, line 296 concerning checkConfiguration unchanged Updating etc/group...unchanged Updating etc/shadow... Exception in ../SRC/parser.c, line 296 concerning checkConfiguration unchanged Updating etc/gshadow...unchanged Ideas? Regards, Volker Weinberg ---------------------------------------------------------------------------- Volker Weinberg email: volker.weinberg(a)physik.uni-muenchen.de Dept.of Physics phone: Univ. of Munich at home: (089) 14 56 09 (Germany) at CIP: (089) 21 80-24 05 address: Andernacher Str. 17 80993 Muenchen ----------------------------------------------------------------------------

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password lenght limit
by jonathan 29 Apr '00

29 Apr '00

I had a 12 character password on my firewall with 6.3, when I rebuilt the system with 6.4 I am now limited to only 8 characters? Did I forget to load something or what is the problem? Thanx

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SuSE Security Announcement - aaa_base
by marc＠suse.de 29 Apr '00

29 Apr '00

-----BEGIN PGP SIGNED MESSAGE----- ______________________________________________________________________________ SuSE Security Announcement Package: aaabase < 2000.1.3 Date: Sat, 29 Apr 2000 14:03:28 GMT Affected SuSE versions: all Vulnerability Type: remove any local file(s) executing attacker supplied commands as non-root SuSE default package: yes Other affected systems: unknown ______________________________________________________________________________ A security hole was discovered in the package mentioned above. Please update as soon as possible or disable the service if you are using this software on your SuSE Linux installation(s). Other Linux distributions or operating systems might be affected as well, please contact your vendor for information about this issue. Please note that we provide this information on an "as-is" basis only. There is no warranty whatsoever and no liability for any direct, indirect or incidental damage arising from this information or the installation of the update package. _____________________________________________________________________________ 1. Problem Description aaa_base is the basic package which comes with any SuSE Linux installation. Two vulnerabilities have been found: 1) The cron job /etc/cron.daily/aaa_base does a daily checking of files in /tmp and /var/tmp, where old files will be deleted if configured to do so. Please note this this feature is NOT activated by default 2) Some system accounts have their homedirectories set to /tmp by default. These are the users games, firewall, wwwrun and nobody on a SuSE 6.4. 2. Impact 1) If the /tmp cleanup is activated, any file or directory can be deleted by any local user 2) If an attacker creates dot files in /tmp (e.g. bash profiles), these might be executed if someone uses e.g. "su - nobody" to switch to the nobody user. This can lead to a compromise of that userid. This vulnerability is present in several other unix systems as well - please check all! 3. Solution 1) Update the package from our FTP server. 2) The root user will receive a email with the accounts listed which have a homedirectory in /tmp. You have to fix this by hand, because some installations might break if they rely on information saved in the (unsafe) /tmp homedirectory. The email will give more information what to do. ______________________________________________________________________________ Please verify these md5 checksums of the updates before installing: 369c48687807875e9b01f24b6e6bb061 ftp://ftp.suse.com/pub/suse/axp/update/6.3/a1/aaa_base-2000.1.3-0.alpha.rpm 350cabc140a177dfa1909d356c982647 ftp://ftp.suse.com/pub/suse/i386/update/6.2/a1/aaa_base-99.9.8-0.i386.rpm 1b0ccf6db229d6c45692588d826853b7 ftp://ftp.suse.com/pub/suse/i386/update/6.3/a1/aaa_base-2000.1.3-0.i386.rpm 34ff11f9ffd877231fab6add4a1723dd ftp://ftp.suse.com/pub/suse/i386/update/6.4/a1/aaa_base-2000.4.27-1.i386.rpm ______________________________________________________________________________ You can find updates on our ftp-Server: ftp://ftp.suse.com/pub/suse/i386/update for Intel processors ftp://ftp.suse.com/pub/suse/axp/update for Alpha processors or try the following web pages for a list of mirrors: http://www.suse.de/ftp.html http://www.suse.com/ftp_new.html Our webpage for patches: http://www.suse.de/patches/index.html Our webpage for security announcements: http://www.suse.de/security If you want to report vulnerabilities, please contact security(a)suse.de ______________________________________________________________________________ SuSE has got two free security mailing list services to which any interested party may subscribe: suse-security(a)suse.com - moderated and for general/linux/SuSE security discussions. All SuSE security announcements are sent to this list. suse-security-announce(a)suse.com - SuSE's announce-only mailing list. Only SuSE's security annoucements are sent to this list. To subscribe to the list, send a message to: <suse-security-subscribe(a)suse.com> To remove your address from the list, send a message to: <suse-security-unsubscribe(a)suse.com> Send mail to the following for info and FAQ for this list: <suse-security-info(a)suse.com> <suse-security-faq(a)suse.com> _____________________________________________________________________________ This information is provided freely to everyone interested and may be redistributed provided that it is not altered in any way. 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openSUSE Security April 2000