Daily Archives: September 7, 2019

Open Sourcing StringSifter

Malware analysts routinely use the Strings program during static analysis in order to inspect a binary's printable characters. However, identifying relevant strings by hand is time consuming and prone to human error. Larger binaries produce upwards of thousands of strings that can quickly evoke analyst fatigue, relevant strings occur less often than irrelevant ones, and the definition of "relevant" can vary significantly among analysts. Mistakes can lead to missed clues that would have reduced overall time spent performing malware analysis, or even worse, incomplete or incorrect investigatory conclusions.

Earlier this year, the FireEye Data Science (FDS) and FireEye Labs Reverse Engineering (FLARE) teams published a blog post describing a machine learning model that automatically ranked strings to address these concerns. Today, we publicly release this model as part of StringSifter, a utility that identifies and prioritizes strings according to their relevance for malware analysis.

Goals

StringSifter is built to sit downstream from the Strings program; it takes a list of strings as input and returns those same strings ranked according to their relevance for malware analysis as output. It is intended to make an analyst's life easier, allowing them to focus their attention on only the most relevant strings located towards the top of its predicted output. StringSifter is designed to be seamlessly plugged into a user’s existing malware analysis stack. Once its GitHub repository is cloned and installed locally, it can be conveniently invoked from the command line with its default arguments according to:

strings <sample_of_interest> | rank_strings

We are also providing Docker command line tools for additional portability and usability. For a more detailed overview of how to use StringSifter, including how to specify optional arguments for customizable functionality, please view its README file on GitHub.

We have received great initial internal feedback about StringSifter from FireEye’s reverse engineers, SOC analysts, red teamers, and incident responders. Encouragingly, we have also observed users at the opposite ends of the experience spectrum find the tool to be useful – from beginners detonating their first piece of malware as part of a FireEye training course – to expert malware researchers triaging incoming samples on the front lines. By making StringSifter publicly available, we hope to enable a broad set of personas, use cases, and creative downstream applications. We will also welcome external contributions to help improve the tool’s accuracy and utility in future releases.

Conclusion

We are releasing StringSifter to coincide with our presentation at DerbyCon 2019 on Sept. 7, and we will also be doing a technical dive into the model at the Conference on Applied Machine Learning for Information Security this October. With its release, StringSifter will join FLARE VM, FakeNet, and CommandoVM as one of many recent malware analysis tools that FireEye has chosen to make publicly available. If you are interested in developing data-driven tools that make it easier to find evil and help benefit the security community, please consider joining the FDS or FLARE teams by applying to one of our job openings.

3 Things You [Probably] Do Online Every Day that Jeopardize Your Family’s Privacy

Even though most of us are aware of the potential risks, we continue to journal and archive our daily lives online publically. It’s as if we just can’t help it. Our kids are just so darn cute, right? And, everyone else is doing it, so why not join the fun?

One example of this has become the digital tradition of parents sharing first-day back-to-school photos. The photos feature fresh-faced, excited kids holding signs to commemorate the big day. The signs often include the child’s name, age, grade, and school. Some back-to-school photos go as far as to include the child’s best friend’s name, favorite TV show, favorite food, their height, weight, and what they want to be when they grow up.

Are these kinds of photos adorable and share-worthy? Absolutely. Could they also be putting your child’s safety and your family’s privacy at risk? Absolutely.

1. Posting identifying family photos

Think about it. If you are a hacker combing social profiles to steal personal information, all those extra details hidden in photos can be quite helpful. For instance, a seemingly harmless back-to-school photo can expose a home address or a street sign in the background. Cyber thieves can zoom in on a photo to see the name on a pet collar, which could be a password clue, or grab details from a piece of mail or a post-it on the refrigerator to add to your identity theft file. On the safety side, a school uniform, team jersey, or backpack emblem could give away a child’s daily location to a predator.

Family Safety Tips
  • Share selectively. Facebook has a private sharing option that allows you to share a photo with specific friends. Instagram has a similar feature.
  • Private groups. Start a private Family & Friends Facebook group, phone text, or start a family chat on an app like GroupMe. This way, grandma and Aunt June feel included in important events, and your family’s personal life remains intact.
  • Photo albums. Go old school. Print and store photos in a family photo album at home away from the public spotlight.
  • Scrutinize your content. Think before you post. Ask yourself if the likes and comments are worth the privacy risk. Pay attention to what’s in the foreground or background of a photo.
  • Use children’s initials. Instead of using your child’s name online, use his or her initials or even a digital nickname when posting. Ask family members to do the same.

2. Using trendy apps, quizzes & challengesfamily privacy

It doesn’t take much to grab our attention or our data these days. A survey recently conducted by the Center for Data Innovation found that 58 percent of Americans are “willing to share their most sensitive personal data” (including medical and location data) in return for using apps and services.

If you love those trendy face-morphing apps, quizzes that reveal what celebrity you look like, and taking part in online challenges, you are likely part of the above statistic. As we learned just recently, people who downloaded the popular FaceApp to age their faces didn’t realize the privacy implications. Online quizzes and challenges (often circulated on Facebook) can open you up to similar risk.

Family Safety Tips

  • Slow down. Read an app’s privacy policy and terms. How will your content or data be used? Is this momentary fun worth exchanging my data?
  • Max privacy settings. If you download an app, adjust your device settings to control app permissions immediately.
  • Delete unused apps. An app you downloaded five years ago and forgot about can still be collecting data from your phone. Clean up and delete apps routinely.
  • Protect your devices. Apps, quizzes, and challenges online can be channels for malicious malware. Take the extra step to ensure your devices are protected.

3. Unintentionally posting personal details

Is it wrong to want an interesting Facebook or Instagram profile? Not at all. But be mindful you are painting a picture with each detail you share. For instance: It’s easy to show off your new dog Fergie and add your email address and phone number to your social profile so friends can easily stay in touch. It’s natural to feel pride in your hometown of Muskogee, to celebrate Katie Beth‘s scholarship and Justin‘s home run. It’s natural to want to post your 23rd anniversary to your beloved Michael (who everyone calls Mickey Dee) on December 15. It’s also common to post about a family reunion with the maternal side of your family, the VanDerhoots.

family privacyWhile it may be common to share this kind of information, it’s still unwise since this one paragraph just gave a hacker 10+ personal details to use in figuring out your passwords.

Family Safety Tips

  • Use, refresh strong passwords. Change your passwords often and be sure to use a robust and unique password or passphrase (i.e., grannymakesmoonshine or glutenfreeformeplease) and make sure you vary passwords between different logins. Use two-factor authentication whenever possible.
  • Become more mysterious. Make your social accounts private, use selective sharing options, and keep your profile information as minimal as possible.
  • Reduce your friend lists. Do you know the people who can daily view your information? To boost your security, consider curating your friend lists every few months.
  • Fib on security questions. Ethical hacker Stephanie Carruthers advises people who want extra protection online to lie on security questions. So, when asked for your mother’s maiden name, your birthplace, or your childhood friend, answer with Nutella, Disneyland, or Dora the Explorer.

We’ve all unwittingly uploaded content, used apps, or clicked buttons that may have compromised our privacy. That’s okay, don’t beat yourself up. Just take a few hours and clean up, lockdown, and streamline your social content. With new knowledge comes new power to close the security gaps and create new digital habits.

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