Facing criticism, Adobe rethinks PDF security

Blasted three months ago for being slow to fix a zero-day vulnerability in its popular PDF viewer, Adobe today promised it will root out bugs in older code, speed up the patching process and release regular security updates for Adobe Reader and Acrobat.

The flak Adobe caught in February, when it disclosed a critical vulnerability, admitted the bug was being used by hackers, but then took weeks to patch the problem, is what prompted Adobe to review its security practices, acknowledged Brad Arkin, Adobe's director for product security and privacy.

"At first, this was just another of our normal security incidents," said Arkin. "But it ended up expanding to [make] changes in our security practices with Reader and Acrobat."

The project, which kicked off in February, has three parts, said Arkin, starting with a look at the legacy code in Reader and Acrobat that he characterized as "at-risk areas."

Currently, Adobe develops new code under what it calls its Secure Product Lifecycle (SPCL), an approach similar to Microsoft's much-better-known Software Development Lifecycle (SDL), which involves several security-specific steps that programmers go through to make their software less liable to harbor bugs. From now on, said Arkin, Adobe will apply the SPCL methodology to some older sections of Reader and Acrobat, too.

"We're going to broadly look at the whole application, but focus on at-risk areas, where we'll do threat modeling, static code analysis and look for potential vulnerabilities," said Arkin, who refused to call that change a full-blown "code review," like the one Microsoft spent millions on to root out bugs in Windows XP.

"We're going to do a lot more pro-active work," he promised. "We want to shake loose vulnerabilities."

Adobe will also speed up its patching and communicate with users more frequently, Arkin said. The company was slapped by some in February for taking three weeks to fix the already-exploited bug, and then only for Reader and Acrobat 9; Adobe staggered the patch delivery for the other versions over several more weeks. A patch for a different zero-day vulnerability that Adobe issued this month was the first step toward that faster pace, said Arkin. "The fact that we were able to patch on May 12, and patch all [editions of] Reader and Acrobat on the same day, that's encouraging," he said.

Adobe will also mimic Microsoft by not only moving to a regular patch delivery schedule, but by going so far as to issue those patches on the same day as Microsoft. "Previously, we did patches on an as-needed basis," said Arkin. "But now we're going to offer them on a [quarterly] basis, and align them with the second Tuesday of the month. Feedback from our customers showed that was a better fit with their processes."

Arkin declined to specify a start date for the quarterly Reader and Acrobat security updates, saying only that they would kick off sometime this summer.

There are some things Adobe won't do, however. Only Reader and Acrobat are involved in the security revamping project, and Adobe won't consider disabling JavaScript in either application. Both recent zero-day vulnerabilities have involved JavaScript, which Adobe has recommended users temporarily switch off until a patch is available.

"No, we won't disable JavaScript by default," said Arkin when asked today. "JavaScript is a really critical feature for our enterprise customers." Instead, he countered that the other measures would result in more secure code while retaining JavaScript. "The code hardening effort will make sure JavaScript is as safe and secure to use as possible," he said.

"The way malware tries to attack people's machines has changed in the last six to twelve months," said Arkin in explaining why Adobe felt the need to revamp its security process.

There's no denying that hackers are exploiting Adobe bugs. According to Finnish security company F-Secure, patching 48.9% of all targeted attacks conducted this year involved a malicious PDF file attached to a legitimate-looking e-mail, a huge change from 2008, when PDFs made up just 28.6% of targeted attacks.

Andrew Storms, director of security operations at nCircle Network Security and a frequent critic of Adobe's practices, welcomed the moves, but wasn't ready to applaud Adobe just yet.

"The proof will be in six months or so," said Storms, "when we see the outcome. Will we see fewer bugs, fewer Reader zero-days? It's always that the proof is in the pudding. But it's welcome that another vendor has stepped up to better protect their customers."

Arkin has written an entry to Adobe's security blog that goes into more detail about the company's new-found Reader security religion.

This story, "Facing criticism, Adobe rethinks PDF security" was originally published by Computerworld.

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