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Security


News and Editorials

The top 20 Internet security vulnerabilities. SANS has posted a list of the 20 most critical security vulnerabilities on the net. The list makes good reading for anybody concerned about the security of their systems, though it is far from a comprehensive list of problems.

The list is broken down into three large sections. The first concerns itself with general, system-independent problems. These include:

  • Default installations of operating systems. Many OS installations leave vulnerabilities, and install more software than is needed.

  • Accounts with nonexistent or weak passwords. Some things haven't changed in decades.

  • Bad backups. This, of course, is a general systems administration problem. If a site's backups have not been checked recently for completeness and restorability, there are probably problems.

  • Large numbers of open ports. Many systems run services they do not need.

  • Lack of address filtering on networks. A properly configured network needs to be sure that both incoming and outgoing packets carry reasonable addresses.

  • Insufficient logging. Without complete and secure logs, detection and analysis of intrusions is impossible.

  • Vulnerable CGI programs. The net probably has not yet begun to see the degree of mayhem that bad CGI programming can cause.

The middle section lists Windows-specific vulnerabilities; readers interested in those are encouraged to go to the SANS page. The final section goes into Unix-specific problems:

  • Buffer overflows in rpc services.

  • Sendmail vulnerabilities. After a relatively quiet period, sendmail seems to be turning up more problems again - see below.

  • Bind vulnerabilities.

  • The rsh, rlogin, and rcp commands, which send passwords in clear text and which enable users to set up uncontrolled webs of trust.

  • Vulnerabilities in the lpd subsystem.

  • Sadmind and mountd. The former is Solaris-specific, but all systems supporting NFS have mountd.

  • Bad SNMP passwords.
A quick look at this list reveals that many of the problems are old, and very few of them are difficult to address. Network security is hard, but, in many cases, even the easy things have not been done.

A survey of PHP vulnerabilities. "Yet Another Hacker Team" has performed an automated audit of a number of PHP-based packages, and has posted the results. The conclusion: much PHP code is vulnerable to remote exploits. Two PHP features are the source of the problems: (1) PHP allows global variables to be set from an HTTP request, and (2) file operations handle URLs transparently. The combination of the two allows a remote attacker to run arbitrary PHP code on the server; this, in turn, gives that attacker shell access.

The survey makes this claim:

PHP is not insecure by default, but makes insecure programming very easy.

Reasonable people could differ on that point. PHP could be far more secure by simply isolating user-supplied information in a special "request" variable. PHP is great stuff (LWN uses a lot of it), but some aspects of the environment are, indeed, insecure by default.

CRYPTO-GRAM special issue. Bruce Schneier has released a special issue of his CRYPTO-GRAM Newsletter devoted to the events of September 11. "People are willing to give up liberties for vague promises of security because they think they have no choice. What they're not being told is that they can have both. It would require people to say no to the FBI's power grab. It would require us to discard the easy answers in favor of thoughtful answers." Worth a read.

Conectiva cuts off 4.x. Conectiva has served notice that the 4.x versions of its distribution are no longer supported, and no further updates will be available. Conectiva customers running ancient versions of the distribution are encouraged to upgrade to something more recent.

Security Reports

OpenSSH 2.9.9 released. OpenSSH 2.9.9 has been released; it includes a security fix that will be important for people using source-based access control.

A new set of sendmail vulnerabilities. Michal Zalewski has found a new set of vulnerabilities in sendmail; they may be used by a local attacker to obtain unauthorized access to the mail system. Versions of sendmail through 8.12 are vulnerable; 8.12.1 has been released and contains fixes for all of the problems. We'll pass on distributor updates as we see them.

Zope DTML scripting security update. There is a new Zope security update out there, fixing a vulnerability in DTML scripting. A suitably clueful user could use the vulnerability to obtain unauthorized access. A fix has been provided by Zope Corp.; expect updates shortly from the distributors that ship Zope as well.

Proprietary products. The following proprietary products were reported to contain vulnerabilities:

  • The Cisco PIX firewall has a vulnerability in its mailguard facility; the restrictions on SMTP commands can be bypassed by an attacker.

Updates

Format string vulnerability in groff. A format string problem exists in groff; apparently it could be remotely exploited when it is configured to be used with the lpd printing system. (First LWN report: August 16, 2001).

The stable release of Debian is not vulnerable.

New updates:

Previous updates:

SQL injection vulnerabilities in Apache authentication modules. Several Apache authentication modules have vulnerabilities that could allow an attacker to feed arbitrary SQL code to the underlying database, resulting in a compromise of database integrity and unauthorized access to the server. See the September 6 security page for more information.

New updates:

Previous updates:

Resources

Linux Security Week from LinuxSecurity.com is available in its October 1 edition. Also available is Linux Advisory Watch for September 28.

CERT has a new PGP key, following the expiration of its previous key at the end of September. See the announcement for the new CERT key information.

Events

The International Cryptography Institute 2001 will be held November 29 and 30 in Washington, DC. Speakers include Dorothy Denning, Whitfield Diffie, Bruce Sterling, and Phil Zimmermann. See the announcement for details.

Upcoming Security Events.
Date Event Location
October 10 - 12, 2001Fourth International Symposium on Recent Advances in Intrusion Detection(RAID 2001)Davis, CA
November 5 - 8, 20018th ACM Conference on Computer and Communication Security(CCS-8)Philadelphia, PA, USA
November 13 - 15, 2001International Conference on Information and Communications Security(ICICS 2001)Xian, China
November 19 - 22, 2001Black Hat BriefingsAmsterdam
November 21 - 23, 2001International Information Warfare SymposiumAAL, Lucerne, Swizerland.
November 24 - 30, 2001Computer Security MexicoMexico City
November 29 - 30, 2001International Cryptography InstituteWashington, DC
December 2 - 7, 2001Lisa 2001 15th Systems Administration ConferenceSan Diego, CA.

For additional security-related events, included training courses (which we don't list above) and events further in the future, check out Security Focus' calendar, one of the primary resources we use for building the above list. To submit an event directly to us, please send a plain-text message to lwn@lwn.net.

Section Editor: Jonathan Corbet


October 4, 2001

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