Welcome to Security Alerts, an overview of recent Unix and open-source security advisories.
In this column, we look at buffer overflows in the Solaris mail utility, Qpopper, and TIAtunnel; temporary-file race conditions in Imp,
ispell; format-string vulnerabilities in GnuPG and
exim; denial-of-service attacks against NetBSD and Fpf; and problems in OpenSSH, the Cisco Content Service Switch, and BestCrypt.
The GNU privacy guard, GnuPG, has a format-string vulnerability that can be used by an attacker to execute arbitrary code with the permissions of the user executing GnuPG. The use of the
--batch parameter (often used when GnuPG is called by an email client) prevents the exploitation of this vulnerability.
It is recommended that users upgrade GnuPG to version 1.0.6.
A vulnerability in NetBSD's IP stack can be attacked by sending a large number of fragmented IP packets. For each fragment that NetBSD receives it will create a reassembly queue that is maintained for 30 seconds. If an attacker quickly sends enough fragmented packets that each have a different IP identification field, the machine may stop communicating on the network. It has been reported that several automated exploits for this vulnerability have been distributed.
It is recommended that systems running NetBSD-current from before April 17, 2001, upgrade to the latest NetBSD-current. Systems running NetBSD 1.5.x dated before April 24, 2001, should upgrade to NetBSD 1.5.x dated after April 24, 2001. These new versions introduce a new
net.inet.ip.maxfragpackets that is used to control the upper limit of reassembly queues.
Alerts this week:
OpenSSH can be manipulated into deleting any file on the system that is named
cookies. This vulnerability only affects OpenSSH clients that have X-forwarding enabled.
This vulnerability has been fixed in the OpenSSH CVS repository. Users of OpenSSH should watch for an updated release or compile a version from the CVS repository.
There is a buffer overflow in the Solaris version of the
/usr/bin/mail program that could be used by an attacker to gain the permissions of the mail group. It has been reported to affect the SPARC and X86 version of Solaris 2.6, 7, and 8.
Users should remove access to
/usr/bin/mail from untrusted users until a patch from SUN has been installed.
Imp, a web-based email client, does not safely create its temporary files when uploading or viewing attachments. This vulnerability creates a race condition that, if exploited, may allow an attacker to overwrite arbitrary files writable by the user running the web server. This vulnerability affects version 1.2.4 but may also affect earlier versions.
Users of Imp should upgrade to version 1.2.5 or newer as soon as possible.
The Cisco Content Service Switch does not properly restrict access to its web management system allowing unauthenticated users access to secure data. This affects versions of Cisco WebNS earlier than 4.01B29s or 4.10B17s.
Users should upgrade as soon as possible to Cisco WebNS version 4.01B29s or 4.10B17s.
The Fpf kernel module alters the Linux TCP/IP stack so that it emulates other operating systems TCP/IP fingerprints and appears to applications such as
queso to be a different OS. A bug in Fpf causes the kernel to panic when the IP stack receives a fragmented packet.
Users should watch for a new version of Fpf that fixes this problem.
The HPUX utility
kmmodreg has a symbolic-link race condition that an attacker can use to overwrite or create arbitrary files.
Users should install patch PHCO_24112 as soon as possible.
BestCrypt allows users to create an encrypted loopback file system. The Linux version of BestCrypt has a vulnerability in the set user ID root utility
bctool that can be used to execute arbitrary code with the permissions of the root user.
Users of BestCrypt should remove the set user ID bit from
bctool and upgrade to version 0.8 as soon as possible.
Qpopper, a server for POP mail, has a buffer overflow that may be exploitable to execute arbitrary code as the root user.
Users should upgrade to version 4.0.3 or newer of Qpopper as soon as possible.
The Message Transfer Agent
exim has a format-string vulnerability that may be exploitable if
headers_check_syntax has been turned on.
exim should watch for a patch.
TIAtunnel, an IRC relay or bouncer, has a remotely executable buffer overflow that can be used by an attacker to execute arbitrary code on the server with the permissions of the user executing TIAtunnel. An automated exploit for this vulnerability has been released.
Users should watch for an updated version of TIAtunnel and should consider turning TIAtunnel off until it has been fixed.
xinetd, under Red Hat Linux 7 and 7.1, is started with a umask of 0. This will cause applications
xinetd starts that do not set their own umask to create world-writable files. It has also been reported that there is a potential buffer overflow in the version of
xinetd distributed with Red Hat Linux 7.
Affected users should upgrade
xinetd to the latest package available from Red Hat.
ispell spell-checking program is vulnerable to a symbolic-link race condition attack. This vulnerability may be used to overwrite files with the permissions of the user executing
Users should upgrade to a patched version of
The VirtualCart Shopping Cart web-based application has a bug that can be exploited by an attacker to execute arbitrary code with the permissions of the user running the web server.
Users of VirtualCart Shopping Cart should contact the vendor for a patch.
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