FTP Buffer Overflows
04/17/2001Welcome 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.
FTP globbing
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.
Pine
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.
Netscape
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
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.
Oracle Application Server
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.
Solaris ipcs
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.
mkpasswd
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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