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[ISN] Should vendors close all security holes?


By Roger A. Grimes
May 11, 2007

In last weeks column, I argued that vendors should close all known 
security holes. A reader wrote me with a somewhat interesting argument 
that Im still slightly debating, although my overall conclusion stands: 
Vendors should close all known security holes, whether publicly 
discussed or not. The idea behind this is that any existing security 
vulnerability should be closed to strengthen the product and protect 
consumers. Sounds great, right?

The reader wrote to say that his company often sits on security bugs 
until they are publicly announced or until at least one customer 
complaint is made. Before you start disagreeing with this policy, hear 
out the rest of his argument.

Our company spends significantly to root out security issues," says the 
reader. "We train all our programmers in secure coding, and we follow 
the basic tenets of secure programming design and management. When bugs 
are reported, we fix them. Any significant security bug that is likely 
to be high risk or widely used is also immediately fixed. But if we 
internally find a low- or medium-risk security bug, we often sit on the 
bug until it is reported publicly. We still research the bug and come up 
with tentative solutions, but we dont patch the problem.

He continues, We have five main arguments for waiting to close a 
noncritical, internally found, security bug. First, in the grand scheme 
of things, wed rather spend our resources on high-risk bugs, whether 
publicly known or unknown. Every medium- or low-risk security bug in the 
pipeline essentially slows down the whole process. We have a fixed 
number of resources. We dont have an unlimited budget like Microsoft.

[Note: Even Microsoft doesnt have an unlimited budget for security 
fixes. -- Roger]

Second, we give next priority to any publicly known bug. We get 
evaluated on the bugs known by the public and how fast we close them. 
You even tout your beloved Secunia.com, and they publicize how fast 
vendors patch known vulnerabilities. People are checking out that site, 
and others, to see how well our product stacks up to the competition. 
Senior management certainly cares how the media portrays us. And nobody, 
not even senior management, knows about the internally found bugs. Wed 
be crazy to concentrate on anything else.

Third, the additional bugs that external hackers find are commonly found 
by examining the patches we apply to our software. Look at our 
vulnerability statistics. Most of our hits center around two main 
features. Both features came to the attention of hackers after we had 
released patches for them fixing internally found problems. In both 
cases we located the vulnerable code and patched. Within a month, three 
more related holes were found by the hacker community. OK, so we didnt 
do a great job in ferreting out all the errors in the features. After 
the last round of fixes, we investigated each feature with a more 
comprehensive analysis and code review. We even hired an external 
penetration testing team. We found many more holes and patched them. 
Then in the next six months, we got hacked again in the same features. 
Theres lots of blame going around, along with better solutions, but it 
doesnt change the fact if we had kept the original exploits unpatched, 
we would have avoided three additional, publicly discussed exploits.

Fourth, every disclosed bug increases the pace of battle against the 
hackers. Its like the anti-virus war. Anti-virus vendors detect each new 
virus and the virus writers make better viruses. Its possible that if 
anti-virus software had never been created, we wouldnt be dealing with 
the level of worm and bot sophistication that we face today. If we patch 
a hole faster than it needed to be patched, it just makes the hackers 
look harder, faster than they otherwise would. We are at the losing end 
of every hacker wannabe in the world, and every fix we have to make 
slows down our product and costs money. Why do we want to encourage a 
better war? If we shut up, when the hacker finally discovers the bug, 
the war proceeds slower, and our customers are on the winning side.

Fifth, when a bug isnt announced, most hackers dont exploit it. The vast 
majority of our customers remain protected, because even if a 
nonpublicly known bug really is known, its only known by a small group 
of hackers. Damage is very limited. Youve said the same thing in one of 
your previous columns that I frequently share with coworkers. Once the 
bug is publicly known, our products come under attack by thousands of 
hackers and dozens of worms. Most of our customers are protected as soon 
as they apply our patches, but for some reason many of our customers 
never patch, or at least dont patch until they call us with their system 
owned and the damage done.

Industry pundits such as yourself often say that it benefits customers 
more when a company closes all known security holes, but in my 25 years 
in the industry, I havent seen that to be true. In fact Ive seen the 
exact opposite. And before you reply, I havent seen an official study 
that says otherwise. Until you can provide me with a research paper, 
everything you say in reply is just your opinion. With all this said, 
once the hole is publicly announced, or becomes high-risk, we close it. 
And we close it fast because we already knew about it, coded a solution, 
and tested it.

On first reading, I thought that there were so many factual mistakes in 
this reader's argument that I didnt know where to begin. But as I 
re-read it, I realized he did make some cognitive points. As Stephen 
Northcutt of SANS taught me, Eat the watermelon and spit out the seeds. 
There is a little truth in every argument.

Roger A. Grimes is contributing editor of the InfoWorld Test Center.

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