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Security Alerts

FTP Buffer Overflows

04/17/2001

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.

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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