Twórcy SuSE Linuksa znaleźli błąd we wszystkich wersjach Samby od 2.0.x do 2.2.7a włącznie. Dzięki niemu dowolna osoba może zmusić smbd do wykonania podstawionego kawałka kodu, a przez to uzyskać prawa administratora na atakowanej maszynie.

Nowa wersja, którą można skopiować ze stron projektu, nie ma już tego błędu. Jednak mimo wszystko zalecane jest zamknięcie nieznanym hostom dostępu do portów 139 i 445.

  Date: Sat, 15 Mar 2003 08:13:20 -0600 (CST)  From: "Gerald (Jerry) Carter"   To: samba@samba.org, samba-announce@samba.org, samba-technical@samba.org  Subject: [SECURITY] Samba 2.2.8 available for download    -----BEGIN PGP SIGNED MESSAGE-----  Hash: SHA1    This release provides an important security fix outlined in the   release notes that follow. This is the latest stable release of   Samba and the version that all production Samba servers should be   running for all current bug-fixes.    The source code can be downloaded from :        http://download.samba.org/samba/ftp/    in the file samba-2.2.8.tar.gz or samba-2.2.8.tar.bz2.  The   uncompressed tarball has been signed using the Samba Distribution   Key (available in the same directory).    Binary packages will be released shortly for major platforms and  can be found at        http://download.samba.org/samba/ftp/Binary_Packages/    As always, all bugs are our responsibility.                               --Sincerely                             The Samba Team                     ****************************************                 * IMPORTANT: Security bugfix for Samba *                 ****************************************    Summary  - -------    The SuSE security audit team, in particular Sebastian Krahmer  , has found a flaw in the Samba main smbd code which  could allow an external attacker to remotely and anonymously gain  Super User (root) privileges on a server running a Samba server.    This flaw exists in previous versions of Samba from 2.0.x to 2.2.7a  inclusive.  This is a serious problem and all sites should either  upgrade to Samba 2.2.8 immediately or prohibit access to TCP ports 139  and 445. Advice created by Andrew Tridgell, the leader of the Samba   Team, on how to protect an unpatched Samba server is given at the end   of this section.    The SMB/CIFS protocol implemented by Samba is vulnerable to many  attacks, even without specific security holes.  The TCP ports 139 and  the new port 445 (used by Win2k and the Samba 3.0 alpha code in  particular) should never be exposed to untrusted networks.    Description  - -----------    A buffer overrun condition exists in the SMB/CIFS packet fragment  re-assembly code in smbd which would allow an attacker to cause smbd  to overwrite arbitrary areas of memory in its own process address  space. This could allow a skilled attacker to inject binary specific  exploit code into smbd.    This version of Samba adds explicit overrun and overflow checks on  fragment re-assembly of SMB/CIFS packets to ensure that only valid  re-assembly is performed by smbd.    In addition, the same checks have been added to the re-assembly  functions in the client code, making it safe for use in other  services.    Credit  - ------    This security flaw was discovered and reported to the Samba Team by  Sebastian Krahmer  of the SuSE Security Audit Team.  The fix was prepared by Jeremy Allison and reviewed by engineers from  the Samba Team, SuSE, HP, SGI, Apple, and the Linux vendor engineers  on the Linux Vendor security mailing list.    The Samba Team would like to thank SuSE and Sebastian Krahmer for  their excellent auditing work and for drawing attention to this flaw.    Patch Availability  - -----------------    As this is a security issue, patches for this flaw specific to earlier  versions of Samba will be posted on the samba-technical@samba.org  mailing list as requested.      ************************************  Protecting an unpatched Samba server  ************************************      Samba Team, March 2003      This is a note on how to provide your Samba server some    protection against the recently discovered remote security    hole if you are unable to upgrade to the fixed version    immediately. Even if you do upgrade you might like to think    about the suggestions in this note to provide you with    additional levels of protection.        Using host based protection    ---------------------------      In many installations of Samba the greatest threat comes for    outside your immediate network. By default Samba will accept    connections from any host, which means that if you run an    insecure version of Samba on a host that is directly    connected to the Internet you can be especially vulnerable.      One of the simplest fixes in this case is to use the 'hosts    allow' and 'hosts deny' options in the Samba smb.conf    configuration file to only allow access to your server from a    specific range of hosts. An example might be:          hosts allow = 127.0.0.1 192.168.2.0/24 192.168.3.0/24      hosts deny = 0.0.0.0/0      The above will only allow SMB connections from 'localhost'    (your own computer) and from the two private networks    192.168.2 and 192.168.3. All other connections will be    refused connections as soon as the client sends its first    packet. The refusal will be marked as a 'not listening on    called name' error.        Using interface protection    --------------------------      By default Samba will accept connections on any network    interface that it finds on your system. That means if you    have a ISDN line or a PPP connection to the Internet then    Samba will accept connections on those links. This may not be    what you want.      You can change this behavior using options like the    following:        interfaces = eth* lo      bind interfaces only = yes      that tells Samba to only listen for connections on interfaces    with a name starting with 'eth' such as eth0, eth1, plus on    the loopback interface called 'lo'. The name you will need to    use depends on what OS you are using. In the above I used the    common name for ethernet adapters on Linux.      If you use the above and someone tries to make a SMB    connection to your host over a PPP interface called 'ppp0',    they will get a TCP connection refused reply. In that    case no Samba code is run at all as the operating system has    been told not to pass connections from that interface to any    process.        Using a firewall    ----------------      Many people use a firewall to deny access to services that    they don't want exposed outside their network. This can be a    very good idea, although I would recommend using it in    conjunction with the above methods so that you are protected    even if your firewall is not active for some reason.      If you are setting up a firewall then you need to know what    TCP and UDP ports to allow and block. Samba uses the    following:        UDP/137    - used by nmbd      UDP/138    - used by nmbd      TCP/139    - used by smbd      TCP/445    - used by smbd      The last one is important as many older firewall setups may    not be aware of it, given that this port was only added to    the protocol in recent years.        Using a IPC$ share deny    -----------------------      If the above methods are not suitable, then you could also    place a more specific deny on the IPC$ share that is used in    the recently discovered security hole. This allows you to    offer access to other shares while denying access to IPC$    from potentially untrustworthy hosts.      To do that you could use:        [ipc$]          hosts allow = 192.168.115.0/24 127.0.0.1          hosts deny = 0.0.0.0/0      this would tell Samba that IPC$ connections are not allowed    from anywhere but the two listed places (localhost and a    local subnet). Connections to other shares would still be    allowed. As the IPC$ share is the only share that is always    accessible anonymously this provides some level of protection    against attackers that do not know a username/password for    your host.        If you use this method then clients will be given a 'access    denied' reply when they try to access the IPC$ share. That    means that those clients will not be able to browse shares,    and may also be unable to access some other resources.      I don't recommend this method unless you cannot use one of    the other methods listed above for some reason.        Upgrading Samba    ---------------      Of course the best solution is to upgrade Samba
 to a version    where the bug has been fixed. If you wish to also use one of    the additional measures above then that would certainly be a    good idea.      Please check regularly on http://www.samba.org/ for updates    and important announcements.                  ****************************************              ****************************************    - -----------------------------------------------------------------    Changes since 2.2.7a  - --------------------    New Parameters        * acl compatibility    Additional Changes:      See the cvs log for SAMBA_2_2 for more details    1)  smbumount lazy patch from Mandrake  2)  Check for too many processes *before* the fork.  3)  make sure we don't run over the end of 'name' in unix_convert()  4)  set umask to 0 before creating socket directory.  5)  Fix the LARGE_SMB_OFF_T problems and allow smbd to do the right      thing in interactive mode when a log file dir is also specified.  6)  Fix delete on close semantics to match W2K.  7)  Correctly return access denied on share mode deny when we can't      open the file.  8)  Always use safe_strcpy not pstrcpy for malloc()'d strings  9)  Fixes for HP-UX only having limited POSIX lock range  10) Added uid/gid caching code. Reduces load on winbindd.  11) Removed extra copy of server name in the printername field (it was      mangling the the name to be \server\serverprinter  12) Fix dumb perror used without errno being set.  13) Do retries correctly if the connection to the DC has failed.  14) Correctly check for inet_addr fail.  15) Ensure we use getgrnam() unless BROKEN_GETGRNAM is defined.  16) Fix for missing if (setting_acls) on default perms.  17) Fix to cache the sidtype  18) fix printer settings on Solaris (big-endian) print servers.      ASCII -> UNICODE conversion bug.  19) Small fix check correct error return.  20) Ensure space_avail is unsigned.  21) patch to check for a valid [f]chmod_acl function pointer      before calling it.  Fixes seg fault in audit VFS module  22) When checking is_locked() new WRITE locks conflict with existing      READ locks even if the context is the same.  23) Merge off-by-one crash fixes from HEAD  24) Move off-by-one buggy malloc()/safe_strcpy() combination to      strdup() instead.  25) Merge from HEAD. Use pstrcpy not safe_strcpy.  26) Fix to allow blocking lock notification to be done rapidly (no wait      for smb -> smb lock release). Adds new PENDING_LOCK type to lockdb      (does not interfere with existing locks).  27) Doxygen cleanups for code documentation  28) limit the unix domain sockets used by winbindd  by adding a      "last_access" field to winbindd connections, and will close      the oldest idle connection once the number of open connections goes      over WINBINDD_MAX_SIMULTANEOUS_CLIENTS (defined in local.h as 200      currently)  29) Fix a couple of string handling errors in smbd/dir.c that would      cause smbd to crash  30) Fix seg fault in smbpasswd when specifying the new password      as a command line argument  31) Correct 64-but file sizes issues with smbtar and smbclient  32) Add batch mode option to pdbedit  33) Add protection in nmbd against malformed reply packets  34) Fix bug with sendfile profiling support in smbstatus output  35) Correct bug in "hide unreadable" smb.conf parameter that      resulted in incorrect directory listings  36) Fix bug in group enumeration in winbindd  37) Correct build issues with libsmbclient on Solaris  38) Fix memory leak and bad pointer dereference in password      changing code in smbd  39) Fix for changing attributes on a file truncate  40) Ensure smbd process count never gets to -1 if limiting number      of processes  41) Ensure we return disk full by default on short writes  42) Don't delete jobs submitted after the lpq time  43) Fix reference count bug where smbds would not terminate      with no open resources  44) Performance fix when using quota support on HP-UX  45) Fixes for --with-ldapsam      * Default to port 389 when "ldap ssl != on"      * add support for rebinding to the master directory server        for password changes when "ldap server" points to a read-only        slave  46) Add -W and -X command line flags to smbpasswd for extracting and      setting the machine/domain SID in secrets.tdb.  See the      smbpasswd(8) man page for details.  47) Added (c) Luke Howard to winbind_nss_solaris.c for coded      obtained from PADL's nss_ldap library.  48) Fix bug in samr_dispinfo query in winbindd  49) Fix segfault in NTLMSSP password changing code for      guest connections  50) Correct pstring/fstring mismatches  51) Send level II oplock break requests synchronously to prevent      condition where one smbd would continually lock a share entry      in locking.tdb  52) Miscellaneous cleanups for tdb error conditions and appending      data in a record  53) Implement correct open file truncate semantics with DOS      attributes  54) Enforce wide links = no on files as well as directories  55) Include shared library checks for Stratus VOS  56) Include support for CUPS printer classes and logging the remote      client name  57) Include  "WinXP" (Windows XP) and "Win2K3" (Windows .NET) values      for %a  58) Increase the max PDU size to deal with some troublesome printer      drivers and Windows NT 4.0 clients  59) increment the process counter immediately after the fork      (not just when we receive the first smb packet)  60) Ensure rename sets errno correctly  61) Unify ACL code (back-port from 3.0)  62) Fix some further issues around off_t and large offsets    -----BEGIN PGP SIGNATURE-----  Version: GnuPG v1.2.0 (GNU/Linux)  Comment: For info see http://quantumlab.net/pine_privacy_guard/    iD8DBQE+czUBIR7qMdg1EfYRAtw3AJ0aOssqot9nSJPrtdciVxb/Q2DxTQCgtHEA  VK0cv2KDuqWWoLesbW1tQpM=  =GIxq  -----END PGP SIGNATURE-----  

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