Entries Tagged "patching"

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Trusted Computing Best Practices

The Trusted Computing Group (TCG) is an industry consortium that is trying to build more secure computers. They have a lot of members, although the board of directors consists of Microsoft, Sony, AMD, Intel, IBM, SUN, HP, and two smaller companies who are voted on in a rotating basis.

The basic idea is that you build a computer from the ground up securely, with a core hardware “root of trust” called a Trusted Platform Module (TPM). Applications can run securely on the computer, can communicate with other applications and their owners securely, and can be sure that no untrusted applications have access to their data or code.

This sounds great, but it’s a double-edged sword. The same system that prevents worms and viruses from running on your computer might also stop you from using any legitimate software that your hardware or operating system vendor simply doesn’t like. The same system that protects spyware from accessing your data files might also stop you from copying audio and video files. The same system that ensures that all the patches you download are legitimate might also prevent you from, well, doing pretty much anything.

(Ross Anderson has an excellent FAQ on the topic. I wrote about it back when Microsoft called it Palladium.)

In May, the Trusted Computing Group published a best practices document: “Design, Implementation, and Usage Principles for TPM-Based Platforms.” Written for users and implementers of TCG technology, the document tries to draw a line between good uses and bad uses of this technology.

The principles that TCG believes underlie the effective, useful, and acceptable design, implementation, and use of TCG technologies are the following:

  • Security: TCG-enabled components should achieve controlled access to designated critical secured data and should reliably measure and report the system’s security properties. The reporting mechanism should be fully under the owner’s control.
  • Privacy: TCG-enabled components should be designed and implemented with privacy in mind and adhere to the letter and spirit of all relevant guidelines, laws, and regulations. This includes, but is not limited to, the OECD Guidelines, the Fair Information Practices, and the European Union Data Protection Directive (95/46/EC).
  • Interoperability: Implementations and deployments of TCG specifications should facilitate interoperability. Furthermore, implementations and deployments of TCG specifications should not introduce any new interoperability obstacles that are not for the purpose of security.
  • Portability of data: Deployment should support established principles and practices of data ownership.
  • Controllability: Each owner should have effective choice and control over the use and operation of the TCG-enabled capabilities that belong to them; their participation must be opt-in. Subsequently, any user should be able to reliably disable the TCG functionality in a way that does not violate the owner’s policy.
  • Ease-of-use: The nontechnical user should find the TCG-enabled capabilities comprehensible and usable.

It’s basically a good document, although there are some valid criticisms. I like that the document clearly states that coercive use of the technology—forcing people to use digital rights management systems, for example, are inappropriate:

The use of coercion to effectively force the use of the TPM capabilities is not an appropriate use of the TCG technology.

I like that the document tries to protect user privacy:

All implementations of TCG-enabled components should ensure that the TCG technology is not inappropriately used for data aggregation of personal information/

I wish that interoperability were more strongly enforced. The language has too much wiggle room for companies to break interoperability under the guise of security:

Furthermore, implementations and deployments of TCG specifications should not introduce any new interoperability obstacles that are not for the purpose of security.

That sounds good, but what does “security” mean in that context? Security of the user against malicious code? Security of big media against people copying music and videos? Security of software vendors against competition? The big problem with TCG technology is that it can be used to further all three of these “security” goals, and this document is where “security” should be better defined.

Complaints aside, it’s a good document and we should all hope that companies follow it. Compliance is totally voluntary, but it’s the kind of document that governments and large corporations can point to and demand that vendors follow.

But there’s something fishy going on. Microsoft is doing its best to stall the document, and to ensure that it doesn’t apply to Vista (formerly known as Longhorn), Microsoft’s next-generation operating system.

The document was first written in the fall of 2003, and went through the standard review process in early 2004. Microsoft delayed the adoption and publication of the document, demanding more review. Eventually the document was published in June of this year (with a May date on the cover).

Meanwhile, the TCG built a purely software version of the specification: Trusted Network Connect (TNC). Basically, it’s a TCG system without a TPM.

The best practices document doesn’t apply to TNC, because Microsoft (as a member of the TCG board of directors) blocked it. The excuse is that the document hadn’t been written with software-only applications in mind, so it shouldn’t apply to software-only TCG systems.

This is absurd. The document outlines best practices for how the system is used. There’s nothing in it about how the system works internally. There’s nothing unique to hardware-based systems, nothing that would be different for software-only systems. You can go through the document yourself and replace all references to “TPM” or “hardware” with “software” (or, better yet, “hardware or software”) in five minutes. There are about a dozen changes, and none of them make any meaningful difference.

The only reason I can think of for all this Machiavellian maneuvering is that the TCG board of directors is making sure that the document doesn’t apply to Vista. If the document isn’t published until after Vista is released, then obviously it doesn’t apply.

Near as I can tell, no one is following this story. No one is asking why TCG best practices apply to hardware-based systems if they’re writing software-only specifications. No one is asking why the document doesn’t apply to all TCG systems, since it’s obviously written without any particular technology in mind. And no one is asking why the TCG is delaying the adoption of any software best practices.

I believe the reason is Microsoft and Vista, but clearly there’s some investigative reporting to be done.

(A version of this essay previously appeared on CNet’s News.com and ZDNet.)

EDITED TO ADD: This comment completely misses my point. Which is odd; I thought I was pretty clear.

EDITED TO ADD: There is a thread on Slashdot on the topic.

EDITED TO ADD: The Sydney Morning Herald republished this essay. Also “The Age.”

Posted on August 31, 2005 at 8:27 AM • View Comments

New Windows Vulnerability

There’s a new Windows 2000 vulnerability:

A serious flaw has been discovered in a core component of Windows 2000, with no possible work-around until it gets fixed, a security company said.

The vulnerability in Microsoft’s operating system could enable remote intruders to enter a PC via its Internet Protocol address, Marc Maiffret, chief hacking officer at eEye Digital Security, said on Wednesday. As no action on the part of the computer user is required, the flaw could easily be exploited to create a worm attack, he noted.

What may be particularly problematic with this unpatched security hole is that a work-around is unlikely, he said.

“You can’t turn this (vulnerable) component off,” Maiffret said. “It’s always on. You can’t disable it. You can’t uninstall.”

Don’t fail to notice the sensationalist explanation from eEye. This is what I call a “publicity attack” (note that the particular example in that essay is wrong): it’s an attempt by eEye Digital Security to get publicity for their company. Yes, I’m sure it’s a bad vulnerability. Yes, I’m sure Microsoft should have done more to secure their systems. But eEye isn’t blameless in this; they’re searching for vulnerabilities that make good press releases.

Posted on August 5, 2005 at 2:25 PM • View Comments

Microsoft Permits Pirated Software to Receive Security Patches

Microsoft wants to make pirated software less useful by preventing it from receiving patches and updates. At the same time, it is in everyone’s best interest for all software to be more secure: legitimate and pirated. This issue has been percolating for a while, and I’ve written about it twice before. After much back and forth, Microsoft is going to do the right thing:

From now on, customers looking to get the latest add-ons to Windows will have to verify that their copy of the operating system is legit….

The only exception is for security-related patches. Regardless of whether a system passes the test, security updates will be available to all Windows users via either manual download or automatic update.

Microsoft deserves praise for this.

On the other hand, the system was cracked within 24 hours.

Posted on July 29, 2005 at 11:26 AM • View Comments

The Potential for an SSH Worm

SSH, or secure shell, is the standard protocol for remotely accessing UNIX systems. It’s used everywhere: universities, laboratories, and corporations (particularly in data-intensive back office services). Thanks to SSH, administrators can stack hundreds of computers close together into air-conditioned rooms and administer them from the comfort of their desks.

When a user’s SSH client first establishes a connection to a remote server, it stores the name of the server and its public key in a known_hosts database. This database of names and keys allows the client to more easily identify the server in the future.

There are risks to this database, though. If an attacker compromises the user’s account, the database can be used as a hit-list of follow-on targets. And if the attacker knows the username, password, and key credentials of the user, these follow-on targets are likely to accept them as well.

A new paper from MIT explores the potential for a worm to use this infection mechanism to propagate across the Internet. Already attackers are exploiting this database after cracking passwords. The paper also warns that a worm that spreads via SSH is likely to evade detection by the bulk of techniques currently coming out of the worm detection community.

While a worm of this type has not been seen since the first Internet worm of 1988, attacks have been growing in sophistication and most of the tools required are already in use by attackers. It’s only a matter of time before someone writes a worm like this.

One of the countermeasures proposed in the paper is to store hashes of host names in the database, rather than the names themselves. This is similar to the way hashes of passwords are stored in password databases, so that security need not rely entirely on the secrecy of the database.

The authors of the paper have worked with the open source community, and version 4.0 of OpenSSH has the option of hashing the known-hosts database. There is also a patch for OpenSSH 3.9 that does the same thing.

The authors are also looking for more data to judge the extent of the problem. Details about the research, the patch, data collection, and whatever else thay have going on can be found here.

Posted on May 10, 2005 at 9:06 AM • View Comments

Pirated Windows to Remain Unpatched

From the Associated Press:

Microsoft Corp. plans to severely curtail the ways in which people running pirated copies of its dominant Windows operating system can receive software updates, including security fixes.

The new authentication system, announced Tuesday and due to arrive by midyear, will still allow people with pirated copies of Windows to obtain security fixes, but their options will be limited. The move allows Microsoft to use one of its sharpest weapons—access to security patches that can prevent viruses, worms and other crippling attacks—to thwart a costly and meddlesome piracy problem.

I’ve written about this before. Unpatched Windows systems on the Internet are a security risk to everyone. I understand Microsoft wanting to fight piracy, but reducing the security of its paying customers is not a good way to go about it.

Posted on February 17, 2005 at 8:00 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.