Buffer Overflow in Samba allows remote root

 Date: Mon, 7 Apr 2003 07:45:16 +0000 (UTC) From: Erik Parker  To: bugtraq@securityfocus.com Subject: [DDI-1013] Buffer Overflow in Samba allows remote root compromise  --[PinePGP]--------------------------------------------------[begin]--  |------------------------------------------------------------------------------|  Digital Defense Inc. Security Advisory DDI-1013        labs@digitaldefense.net  https://www.digitaldefense.com |------------------------------------------------------------------------------|  Synopsis          : Buffer Overflow in Samba allows remote root compromise Package           : Samba, Samba-TNG Type              : Remote Root Compromise Issue date        : 04-07-2003 Versions Affected : = Samba 2.0.10,  < Samba-TNG 0.3.2 Not Affected      : Samba 3.0 Alpha Versions, CVS Versions of Samba-TNG CVE Id            : CAN-2003-0201  |------------------------------------------------------------------------------|   o Product description:    Samba is an Open Source/Free Software suite that provides seamless file and    print services to SMB/CIFS clients. Samba-TNG was originally a fork off of    the Samba source tree, and aims at being a substitute for a Windows NT domain    controller.   o Problem description:    An anonymous user can gain remote root access due to a buffer overflow caused    by a StrnCpy() into a char array (fname) using a non-constant length    (namelen).     StrnCpy(fname,pname,namelen);    /* Line 252 of smbd/trans2.c */     In the call_trans2open function in trans2.c, the Samba StrnCpy function    copies pname into fname using namelen. The variable namelen is assigned the    value of strlen(pname)+1, which causes the overflow.     The variable 'fname' is a _typedef_ pstring, which is a char with a size of    1024. If pname is greater than 1024, you can overwrite almost anything you    want past the 1024th byte that fits inside of sizeof(pname), or the value    returned by SVAL(inbuf,smbd_tpscnt) in function reply_trans2(), which should    be around 2000 bytes.     The Common Vulnerabilities and Exposures (CVE) project has assigned the name    CAN-2003-0201 to this issue. This is a candidate for inclusion in the CVE    list (http://cve.mitre.org), which standardizes names for security problems.   o Testing Environment:    Tested against source compiles and binary packages of Samba from version    2.2.5 to 2.2.8 on the following x86 platforms:     Red Hat Linux 7.1, 7.3, 8.0    Gentoo Linux 1.4-rc3    SuSe Linux 7.3    FreeBSD 4.6, 4.8, 5.0    Solaris 9   o Solutions and Workarounds:    Upgrading to the latest version of Samba or Samba-TNG is the recommended    solution to this vulnerability. Samba version 2.2.8a, and Samba-TNG version    0.3.2 are not vulnerable. There will be no new releases for the 2.0 line of    Samba code. The only fix for Samba 2.0 is to apply the patches that Samba is    providing.     A workaround in the current source code for this specific vulnerability    would be to modify the StrnCpy line found at line 250 in smbd/trans2.c in the    Samba 2.2.8 source code:     -StrnCpy(fname,pname,namelen);    +StrnCpy(fname,pname,MIN(namelen, sizeof(fname)-1));     As a result of this vulnerability being identified at least three others    have also been found by the Samba team after reviewing similar usages in the    source tree. One is a static overflow and the other two are heap overflows.    Applying the fix above will only protect against the specific problem    identified in this advisory. To fully protect yourself, you must apply the    patches from Samba, or upgrade to 2.2.8a.     Samba is available for download from: Samba - opening windows to a wider world    Samba-TNG is available for download from:     o Exploit:    An exploit named trans2root.pl has been posted on the Digital Defense, Inc.    website. A quick udp based based scanner named nmbping.pl has also been    posted to assist you in identifying Samba servers on your network. Both are    available for download from the following URL:          This exploit works against all distributions listed in the testing    environment section. Usage is as follows:     trans2root.pl  -t  -H  -h      This exploit should work against all x86 Linux, Solaris, and  FreeBSD hosts    running the 2.2.x branch of Samba. Hosts with a non-executable stack are not    vulnerable to this particular exploit. The exploit will cause the target host    to connect back to the host running the exploit and spawn a root shell on the    defined port (default is 1981).     The scanner is very easy to use, and should detect and identify Samba and    Windows SMB services. Usage is as follows:     nmbping.pl    o Forced Release:    This vulnerability is being actively exploited in the wild. Digital Defense,    Inc. discovered this bug by analyzing a packet capture of an attack against a    host running Samba 2.2.8. The attack captured was performed on April 1st,    2003. Samba users are urged to check their Samba servers for signs of    compromise. Samba and Digital Defense, Inc. decided to release their    advisories before all vendors had a chance to update their packages due to    this vulnerability being actively exploited.   o Revision History:    04-07-2003     Initial public release     Latest revision available at:    https://www.digitaldefense.com   o Vendor Contact Information:    04-03-2003     security@samba.org notified    04-03-2003     elrond@samba-tng.org notified.    04-03-2003     Samba Team responds via telephone, acknowledges vulnerability    04-03-2003     Elrond of Samba-TNG responds and acknowledges vulnerability    04-04-2003     Samba Team notifies vendorsec mailing list    04-07-2003     Initial public release  o Thanks to:    Elrond of Samba-TNG, The Samba Security Team, and everyone on the    Digital Defense Inc., SECOPS team.  --[PinePGP]----------------------------------------------------------- gpg: Signature made Mon 07 Apr 2003 05:08:09 AM EDT using DSA key ID 864A8D20 gpg: Can't check signature: public key not found PinePGP: Encryption backend encountered error. --[PinePGP]----------------------------------------------------[end]--