Google researcher calls for Flash flush

10,000 sites need scrubbing (or more)


A Google researcher is advising that security professionals rewrite code associated with Adobe Flash content two weeks after warning that buggy files can be exploited by attackers to gain complete control over transactions on websites belonging to banks, government agencies and other trusted organizations.

The security bug resides in SWF files created by most of the most common programs for generating the ubiquitous Flash applets that animate sites across the web. Vulnerable content opens websites up to cross-site scripting (XSS) exploits that allow an attacker to perform any action available to a user of the targeted website. Criminals could use it to pilfer a users' account details or perform withdrawals on behalf of a customer.

Adobe, Autodemo, TechSmith and InfoSoft have updated their content generation products so they no longer produce buggy SWF files, according to this post from Rich Cannings, a senior information security engineer at Google who helped discover the vulnerability. He advised security professionals to remove vulnerable SWF files from websites and regenerate them following the manufacturers' advice.

Cannings recommended security pros take other steps. They include serving automatically generated SWF files from numbered IP addresses or from domains that are separate from trusted sites that contain sensitive cookies or other credentials that could be used in phishing attacks. Or security people may opt to move or remove all third-party generated SWF files entirely, he said.

"If there's an issue on a bank, the impact of an XSS is pretty large," said Cannings. In other words, it's a huge amount of work, but well worth it for trusted sites that want to remain that way.

Security pros and Flash authors may also want to use Stafano Di Paola's SWFIntruder to check for vulnerabilities in their content.

When we first reported the Flash vulnerability two weeks ago, some Reg readers complained the article didn't detail exactly how the vulnerability worked. Now that patches are available, Cannings is willing to say a bit more.

Flash files produced by Adobe DreamWeaver contain a "skinName" parameter that can be exploited to force victims to load arbitrary URLs that include the "asfunction" protocol handler. SWF files generated with Adobe Acrobat Connect don't properly validate the "baseurl" parameter, allowing script injection. Content produced by TechSmith Camtasia contain a "csPreloader" parameter that loads an arbitrary flash file.

The vulnerability is documented in the book Hacking Exposed Web 2.0: Web 2.0 Security Secrets and Solutions, which is hitting store shelves now. In addition to Cannings, it was written by Himanshu Dwivedi, Zane Lackey, Chris Clark and Alex Stamos of iSEC Partners. It is published by The McGraw-Hill Companies.

The buggy Flash files are known to be contained on tens of thousands of websites, many belonging to banks, government agencies and major corporations, according to the authors, who relied on Google searches for their estimate. The actual number of sites could be in the hundreds of thousands because vulnerable files don't always turn up in web searches, they said. ®


Keep Reading

Tech Resources

The State of Application Security 2020

Forrester analyzed the state of application security in 2020 and found over 75% of external attacks are attributed to web application and software exploits.

How backup modernization changes the ransomware game

If the thrill of backing up your data and wondering if you will ever see it again has worn off, start the new year by getting rid of the lingering pain of legacy backup. Bipul Sinha, CEO of the Cloud Data Management Company, Rubrik, and Miguel Zatarain, Director of Global Infrastructure Technology at PACCAR, Fortune 500 manufacturer of trucks and Rubrik customer, are talking to the Reg’s Tim Phillips about how to eliminate the costly, slow and spotty performance of legacy backup, and how to modernize your implementation in 2021 to make your business more resilient.

Webcast Slide Deck | Three reasons you need a hybrid multicloud

Businesses need their IT teams to operate applications and data in a hybrid environment spanning on-premises private and public clouds. But this poses many challenges, such as managing complex networking, re-architecting applications for the cloud, and managing multiple infrastructure silos. There is a pressing need for a single platform that addresses these challenges - a hybrid multicloud built for the digital innovation era. Just this Regcast to find out: Why hybrid multicloud is the ideal path to accelerate cloud migration.

Anatomy of a Private Cloud

Learn the key elements that combined, build a true Private Cloud

Biting the hand that feeds IT © 1998–2021