Yahoo says attackers looking for Shellshock found a different bug

The bug has now been fixed and user data was not at risk, the company said

Yahoo said Monday it has fixed a bug that was mistaken for the Shellshock flaw, but no user data was affected.

Three of the company's servers with APIs (application programming interfaces) that provide live streaming for its Sports service "had malicious code executed on them this weekend by attackers looking for vulnerable Shellshock servers," wrote Alex Stamos, Yahoo's chief information security officer.

Stamos wrote on the Hacker News website that the servers had been patched after the Shellshock vulnerability was disclosed.

Yahoo was notified by Jonathan Hall, senior engineer and president of Future South Technologies, a security consulting firm. Hall wrote on his blog that he uncovered a vulnerability in at least two Yahoo servers.

Hall wrote he found evidence that a group of what appears to be Romanian hackers had struck Yahoo, Lycos and WinZip, using the Shellshock vulnerability to infect servers and build a botnet, the term for a network of infected machines.

Shellshock, first identified late last month, is the nickname for a flaw in a form of software known as Bash, a command-line shell processor on Unix and Linux systems. The security hole could let attackers insert extra code into computers running Bash, allowing them to take control of servers remotely.

In a statement released earlier on Monday, Yahoo appeared to confirm Hall's finding that Shellshock was to blame. But Stamos later published a post on the Hacker News saying that further investigation showed Shellshock was not the cause.

The attackers, Stamos wrote, had "mutated" their exploit and ended up taking advantage of a different bug that was in a monitoring script being run by Yahoo's developers to parse and debug Web logs. That bug was only specific to a small number of machines, he wrote.

"As you can imagine this episode caused some confusion in our team, since the servers in question had been successfully patched (twice!!) immediately after the Bash issue became public," he wrote.

Hall wrote that he sent an email warning of his findings to WinZip, a division of Canada-based Corel. WinZip is a file compression utility.

In an email statement on Monday, WinZip spokeswoman Jessica Gould didn't directly address Hall's findings but said "we were contacted by Mr. Hall almost a week after we began our patching process. We've since replied to Mr. Hall directly to thank him for contacting us."

Hall wrote on his blog that it appeared WinZip's servers had been compromised using Shellshock. Those servers were then being used to search for other vulnerable Web servers. The malicious code on WinZip's servers connected to an IRC server, where it awaits commands from the hackers.

(Zach Miners in San Francisco contributed to this report.)

Join the CSO newsletter!

Error: Please check your email address.

Tags winzipYahoocorelsecuritydata breachDesktop securityFuture South TechnologiesLycosdata protection

More about CorelLinuxLycosNewsWinZipYahoo

Show Comments

Featured Whitepapers

Editor's Recommendations

Solution Centres

Stories by Jeremy Kirk

Latest Videos

  • 150x50

    CSO Webinar: The Human Factor - Your people are your biggest security weakness

    ​Speakers: David Lacey, Researcher and former CISO Royal Mail David Turner - Global Risk Management Expert Mark Guntrip - Group Manager, Email Protection, Proofpoint

    Play Video

  • 150x50

    CSO Webinar: Current ransomware defences are failing – but machine learning can drive a more proactive solution

    Speakers • Ty Miller, Director, Threat Intelligence • Mark Gregory, Leader, Network Engineering Research Group, RMIT • Jeff Lanza, Retired FBI Agent (USA) • Andy Solterbeck, VP Asia Pacific, Cylance • David Braue, CSO MC/Moderator What to expect: ​Hear from industry experts on the local and global ransomware threat landscape. Explore a new approach to dealing with ransomware using machine-learning techniques and by thinking about the problem in a fundamentally different way. Apply techniques for gathering insight into ransomware behaviour and find out what elements must go into a truly effective ransomware defence. Get a first-hand look at how ransomware actually works in practice, and how machine-learning techniques can pick up on its activities long before your employees do.

    Play Video

  • 150x50

    CSO Webinar: Get real about metadata to avoid a false sense of security

    Speakers: • Anthony Caruana – CSO MC and moderator • Ian Farquhar, Worldwide Virtual Security Team Lead, Gigamon • John Lindsay, Former CTO, iiNet • Skeeve Stevens, Futurist, Future Sumo • David Vaile - Vice chair of APF, Co-Convenor of the Cyberspace Law And Policy Community, UNSW Law Faculty This webinar covers: - A 101 on metadata - what it is and how to use it - Insight into a typical attack, what happens and what we would find when looking into the metadata - How to collect metadata, use this to detect attacks and get greater insight into how you can use this to protect your organisation - Learn how much raw data and metadata to retain and how long for - Get a reality check on how you're using your metadata and if this is enough to secure your organisation

    Play Video

  • 150x50

    CSO Webinar: How banking trojans work and how you can stop them

    CSO Webinar: How banking trojans work and how you can stop them Featuring: • John Baird, Director of Global Technology Production, Deutsche Bank • Samantha Macleod, GM Cyber Security, ME Bank • Sherrod DeGrippo, Director of Emerging Threats, Proofpoint (USA)

    Play Video

  • 150x50

    IDG Live Webinar:The right collaboration strategy will help your business take flight

    Speakers - Mike Harris, Engineering Services Manager, Jetstar - Christopher Johnson, IT Director APAC, 20th Century Fox - Brent Maxwell, Director of Information Systems, THE ICONIC - IDG MC/Moderator Anthony Caruana

    Play Video

More videos

Blog Posts