Security

mgetty can be configured to run an external program to decide whether or not to answer an incoming call based on Caller ID information. Unpatched versions of mgetty prior to 1.1.29 would overflow an internal buffer if the caller name reported by the modem was too long.

Additionally, the faxspool script supplied with versions of mgetty prior to 1.1.29 used a simple permissions scheme to allow or deny fax transmission privileges. This scheme was easily circumvented because the spooling directory used for outgoing faxes was world-writable.

A remote root vulnerability in slave setups and some buffer overflows in the network information server code were discovered by the apcupsd developers. They have been fixed in the latest unstable version, 3.10.5 which contains additional enhancements like USB support, and the latest stable version, 3.8.6.

There are a few changes that need to be noted, such as the port has changed from port 7000 to post 3551 for NIS, and the new config only allows access from the localhost. Users may need to modify their configuration files appropriately, depending upon their configuration.

Unfortunatly that does not mean that Linux systems are not vulnerable. Similar code, without Olaf Firch's fixes, is in the glibc getnetbyXXX functions. These functions are described in the SuSE alert as " used by very few applications only, such as ifconfig and ifuser, which makes exploits less likely."

CERT Advisory: CA-2002-19 Buffer Overflow in Multiple DNS Resolver Libraries

CAN-2002-0651
CAN-2002-0684

A denial of service vulnerability exists in BitchX. Sending a malformed RPL_NAMREPLY numeric 353 causes BitchX to segfault. This problem was reported to panasync@efnet#bitchx on Jan 30 2003, as of this writing we are unaware of any patches or workarounds provided by panasync and or any members of #bitchx

A buffer overflow bug in the Canna server up to and including version 3.5b2 allows a local user to gain the privileges of the user 'bin' which could lead to further exploits. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CAN-2002-1158 to this issue.

A lack of validation of requests has been found that affects Canna version 3.6 and earlier. A malicious remote user could exploit this vulnerability to leak information, or cause a denial of service attack. (CAN-2002-1159)

See also http://canna.sourceforge.jp/sec/Canna-2002-01.txt

CAN-2002-1158
CAN-2002-1159

On servers which are configured to allow anonymous read-only access, this bug could be used by anonymous users to gain write privileges. Users with CVS write privileges can then use the Update-prog and Checkin-prog features to execute arbitrary commands on the server.

All users of CVS are advised to upgrade to erratum packages which contain patches to correct the double-free bug.

See also this CERT advisory

When the dhcp-relay receives a BOOTP request it forwards the request to the DHCP server using the broadcast MAC address ff:ff:ff:ff:ff:ff which causes the network interface to reflect the packet back into the socket. To prevent loops the dhcrelay checks whether the relay-address is its own, in which case the packet would be dropped. In combination with a missing upper boundary for the hop counter an attacker can force the dhcp-relay to send a continuing packet storm towards the configured dhcp server(s).

This patch introduces a new commandline switch ``-c maxcount'' and people are advised to start the dhcp-relay with ``dhcrelay -c 10'' or a smaller number, which will only create that many packets.

The dhcrelay program from the ``dhcp'' package does not seem to be affected since DHCP packets are dropped if they were apparently relayed already.

Ximian Evolution is a personal and workgroup information management solution for Linux and UNIX-based systems. The software integrates email, calendaring, meeting scheduling, contact management, and task lists, in one application.

Updating as soon as practical is a good idea.

CERT/CC Vulnerability Note VU#192995 Integer overflow in xdr_array() function when deserializing the XDR stream

The BIND 4 and BIND 8.2.x stub resolver libraries, and other libraries such as glibc 2.2.5 and earlier, libc, and libresolv, uses the maximum buffer size instead of the actual size when processing a DNS response, which causes the stub resolvers to read past the actual boundary ("read buffer overflow"), allowing remote attackers to cause a denial of service (crash).

OpenAFS kaserver implements version 4 of the Kerberos protocol, and therefore is also vulnerable.

The uml_net utility in kernel-utils packages with Red Hat Linux 8.0 was incorrectly shipped setuid root. This could allow local users to control certain network interfaces, add and remove arp entries and routes, and put interfaces in and out of promiscuous mode.

All users of the kernel-utils package should update to these packages that contain a version of uml_net that is not setuid root.

Alternatively, as a work-around to this vulnerability issue the following command as root:

chmod -s /usr/bin/uml_net

CAN-2002-1405

Note that mail processing programs which use this package can be affected by this vulnerability; in particular, SpamAssassin is vulnerable if you use the -r or -w flags.

The problem has been fixed in Mutt 1.4.1 (stable) and 1.5.4 (unstable).

Read the the full advisory for the details.

Note that falconseye does not contain the file permission error CAN-2003-0359 which affected some other nethack packages.

Typically, RSA blinding is not enabled by OpenSSL based applications, mainly because it is not obvious how to do so when using OpenSSL to provide SSL/TLS. This problem affects mostly all applications using OpenSSL and have to be rebuilded against the fixed OpenSSL version (where RSA blinding is now enabled by default) or have to enable RSA blinding explicitly their own.

The performance impact of RSA blinding appears to be small (a few percent only) and the RSA functionality is still fully compatible. The Common Vulnerabilities and Exposures (CVE) project assigned the id CAN-2003-0147 to the problem.

Andreas Beck discovered that versions of pam_xauth supplied with Red Hat Linux since version 7.1 would forward authorization information from the root account to unprivileged users. This could be used by a local attacker to gain access to an administrator's X session. In order to exploit this vulnerability, the attacker would have to get the administrator, as root, to use su to the account belonging to the attacker.

CAN-2002-0985
CAN-2002-0986

CAN-2002-1119

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.

See this article for more information. Samba-TNG users should update to version 0.3.1.

In addition to the above problem the tcpdump developers discovered a potential infinite loop when parsing malformed BGP packets. They also discovered a buffer overflow that can be exploited with certain malformed NFS packets.

The VNC server acts as an X server, but the script for starting it generates an MIT X cookie (which is used for X authentication) without using a strong enough random number generator. This could allow an attacker to be able to more easily guess the authentication cookie.

The VNC DES authentication scheme is implemented using a challenge-response architecture, producing a random and different challenge for each authentication attempt. A bug in the function for generating the random challenge caused the random seed to get reset to the current time on every authentication attempt. Therefore, two authentication attempts within the same second could receive the same challenge. An eavesdropper could exploit this vulnerability by replaying the response, thereby gaining authentication.

All users of VNC are advised to upgrade to these erratum packages, which contain patches to correct these issues.

Users of vsftpd who make use of tcp_wrappers features are advised to upgrade to these errata packages.

This issue only affects Red Hat Linux 9 boxed sets manufactured for distribution within the United States. The part numbers, which can be found on the bottom flap of the box, are RHF0120US and RHF0121US. Copies of Red Hat Linux 9 obtained through other means (such as from Red Hat Network, FTP, or international boxed sets) already contain the packages referenced by this erratum, and are not vulnerable to this issue.

FTP clients must check to see if an FTP server's response to the NLST command includes any directory information along with the list of filenames required by the FTP protocol (RFC 959, section 4.1.3).

If the FTP client fails to do so, a malicious FTP server can send filenames beginning with '/' or containing '/../' which can be used to direct a vulnerable FTP client to write files (such as .forward, .rhosts, .shosts, etc.) that can then be used for later attacks against the client machine.

See also this Bugtraq article from 1997.

CAN-2002-1344

Many Linux systems do not run libgtop by default, but applying the update is a good idea anyway.

CAN-2002-0818