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Alerts this week: • Pine • Netscape • mkpasswd • Alcatel ADSL-Ethernet Bridges • HylaFAX • cfingerd |
Welcome to Security Alerts, an overview of recent Unix and open-source
security advisories. In this column, we look at buffer overflows in
many FTP daemons, Oracle Application Server, Solaris ipcs, Solaris
Xsun, and a whole list of programs in SCO OpenServers; temporary file
race conditions in pine and pico; format string bugs in HylaFAX and
cfingerd; a bug that allows Netscape to execute JavaScript placed in a GIF comment; and
problems in Midnight Commander, mkpasswd, Alcatel ADSL-Ethernet
Bridges, and Interscan VirusWall.
Many FTP daemons are vulnerable to a buffer overflow attack when
executing FTP commands such as CWD, DELE, MKD, and STOU that use the
glob() function call. Systems that are vulnerable to this type of attack include: FreeBSD 4.2, OpenBSD 2.8, NetBSD 1.5, IRIX 6.5.x, HPUX
11, Solaris 2.6, Solaris 7, and Solaris 8.
It has been reported that
NcFTPd and vsftpd are not vulnerable to this attack. It is not clear
which daemons have a remotely exploitable condition and which have
only a denial-of-service vulnerability.
Users should watch their vendors for an update for their FTP daemons.
The pine email package, including the pico editor, does not properly create temporary files. A race condition in the creation of these temporary files can be used by a malicious user to overwrite arbitrary files on the system with the permissions of the user executing pine or pico.
This race condition has been fixed in pine 4.33 and it is recommended that users of pine upgrade as soon as possible.
Under some circumstances, Netscape can be made to execute JavaScript code embedded inside a GIF comment. A remote attacker may be able to exploit this bug and obtain data stored on the local machine. This problem affects Netscape version 4.76.
Users should disable JavaScript or upgrade to Netscape 4.77 or newer.
Midnight Commander is a Ncurses console-based file manager for Unix systems. A vulnerability has been discovered that can be exploited by a malicious user to execute arbitrary commands as the user running Midnight Commander. The attacker exploits the vulnerability by creating directories with carefully crafted names that are then parsed by Midnight Commander as it traverses these directories.
Anyone using Midnight Commander should upgrade to version 4.5.51 or newer as soon as possible.
It has been reported that Oracle Application Server 4.0.8.2 has a
buffer overflow in the shared library ndwfn4.so that is exploitable
when used by the iPlanet Web Server.
Although Oracle has been unable to duplicate this problem, users should watch Oracle for a patch if one becomes available.
The Solaris ipcs application has a buffer overflow in its use of the
TIMEZONE environmental variable that may be exploited by a malicious
user to gain root user privileges.
It is recommended that users remove the set user ID bit from ipcs and
watch Sun for a patch.
The expect script mkpasswd shipped with Red Hat Linux versions 6.2 and 7 generates a small total number of potential passwords. The small
number of potential passwords introduces a vulnerability that can be
used by an attacker to minimize the time necessary to find user
passwords using a dictionary-based password-cracking program.
Users of Red Hat Linux versions 6.2 or 7 should check the Red Hat Web site for updated versions, and should manually select their passwords until mkpasswd has
been fixed.
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The Solaris Xsun application has a buffer overflow that can be exploited by a local user to execute arbitrary code with elevated permissions. The SPARC version of Solaris has Xsun installed "set user group root," while the X86 versions of Solaris have Xsun installed "set user ID root."
If Xsun is executed via dtlogin or xdm, users can remove the set user ID and set group ID bits without losing any functionality. Users
should watch the Sun web site for a patch.
A set of problems in the Alcatel ADSL-Ethernet bridge can allow a remote attacker to modify the bridge's configuration, upload new firmware, and stop it from communicating with the ADSL provider. The following problems have been reported. By default, these devices ship with no password set; if the password was set by the user, it can be retrieved by an attacker using TFTP. There is also a cryptographic back door that can be used to bypass the password and other security features.
Users should check the Alcatel web site for updated firmware.
HylaFAX is an application used to send and receive facsimiles, and send alphanumeric pages. It has been reported that there is a format string bug in HylaFAX that may be exploited to gain root privileges.
Anyone using HylaFAX should watch for confirmation and a fix for this problem.
Cfingerd, a configurable replacement for the finger daemon, has a
format string vulnerability that can be used by a remote attacker to
obtain root privileges. This vulnerability affects version 1.4.3 and
earlier.
Users of cfingerd should disable the daemon until a fix has been made
to the software.
Buffer overflows have been found in SCO OpenServer 5.0.00 through 5.0.6. Applications found to have buffer overflows include:
/usr/bin/accept/usr/bin/cancel/usr/mmdf/bin/deliver/usr/bin/disable/usr/bin/enable/usr/lib/libcurses.a/usr/bin/lp/usr/lib/lpadmin/usr/lib/lpfilter/usr/lib/lpforms/usr/lib/lpmove/usr/lib/lpshut/usr/bin/lpstat/usr/lib/lpusers/usr/bin/recon/usr/bin/reject/usr/bin/rmail/usr/lib/sendmail/usr/bin/tputAll administrators of affected SCO OpenServer systems should install the SSE072B patch dated April 11, 2001.
Trend Micro Interscan VirusWall, a real-time virus detection and clean-up tool that runs on Linux and other Unix systems, has several bugs that could allow a remote attacker to obtain root privileges.
Users should upgrade to Interscan VirusWall version 3.6 as soon as possible.
Noel Davis works as a Unix system administrator. He first started using Unix in 1994 when he purchased a copy of Yggdrasil Plug-and-play Linux Summer 1994 Release.
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