This Month in Cybersecurity: February 2023

Major News Stories

SH1MMER: Chromebook Exploit (and “Possibly the Most-Tortured Acronym Ever”)

SH1MMER is a new exploit for Google’s Chromebooks. It stands for, “Shady Hacking 1nstrument Makes Machine Enrollment Retreat”…OK. Much more helpfully, the site asks:

What is SH1MMER?

SH1MMER is an exploit capable of completely unenrolling enterprise-managed Chromebooks. It was found by the Mercury Workshop team and was released on January, Friday the 13th, 2023.

Google is reportedly looking into the exploit and no fix is available as of yet. Per the earlier source, school districts could be the primary victims of this attack, which works as follows:

Discovered by the Mercury Workshop team and released on Friday, Jan. 13, SH1MMER references a shim, an RMA disk image that’s used by service techs to reinstall an OS and run diagnostics and repair programs. A hacker could install it on a USB drive and then use it to boot up a Chromebook that then shows an altered recovery menu that lets the hacker unenroll the device.

Google Chrome Release Changes

Starting with version 110, some Google Chrome users will start receiving an “early stable version”. According to Google, the motivation is to find problems earlier before they’re released to all users.

Currently, it doesn’t appears that users can opt into or out of receiving an early stable version.

2FA Bypass Discovery Nets Researcher Highest Facebook Bounty Reward

Back in September of 2022, Gtm Mänôz from Kathmandu, Nepal discovered a two-factor authentication bypass in Instagram:

Summary: I discovered the lack of rate-limiting issue in instagram which could have allowed an attacker to bypass two factor authentication on facebook by confirming the targeted user’s already-confirmed facebook mobile number using the Meta Accounts Center.

Gtm states that this was his “first ever” bug bounty write-up. It netted him a cool $163,000 bounty, plus another $24,700 in bonuses. Furthermore, Gtm writes that his report, “was highlighted as one of the most impactful bug [sic] submitted during 2022.”

Patch all the Open* Things

The latest version of OpenSSH (tool for gaining a secure shell on a remote system) is 9.2. It fixes several security vulnerabilities, including a memory safety problem. A great deep-dive on the vulnerability is available here.

OpenSSL, used among other things to secure websites when connecting to them via HTTPS, also patched a memory vulnerability:

The above just underscore the importance of new memory-safe programming languages like Rust.

Redis Under Attack

A new strain of malware dubbed HeadCrab is targeting Redis servers worldwide. So far, the malware has infected at least 1,200 Redis servers and is able to evade detection by virus scanners.

Aquasec has a great write-up on HeadCrab here. Regarding the attack flow, they write:

This story begins with an attack on one of our honeypots when a threat actor targeted a Redis server. The server was eventually compromised using the SLAVEOF command, setting it as a Slave server of another Redis server controlled by the attacker. The Master Redis server then initiated a synchronization of the Slave server which in turn downloaded a malicious Redis module, the HeadCrab malware, onto the Slave server (our honeypot). This technique has been utilized by attackers for some time and allows them to load malicious Redis modules onto affected hosts.

Microsoft in the News

Lots of Microsoft news this month. Here are some top headlines:

AI-powered Bing Chat spills its secrets via prompt injection attack

By instructing Bing Chat to “ignore previous instructions” and write out what is at the “beginning of the document above”, Stanford University student Kevin Liu was able to get Bing chat to divulge its internal codename (Sydney) as well as other behind-the-scenes guidelines the chat bot is supposed to follow. Ars notes that the attack worked much like a typical social engineering attack against humans (!).

Microsoft February 2023 Patch Tuesday

Microsoft…patched 80 different vulnerabilities. This includes the Chromium vulnerabilities affecting Microsoft Edge. Nine vulnerabilities are rated as “Critical” by Microsoft.

Three of the vulnerabilities, all rated “important”, are already being exploited.

Sadly, there were some issues with some of the patches, including Windows Server 2022 not starting up - yikes!

Apple Patches Explointed Vulnerability

Webkit, the rendering engine used by Safari, had a critical vulnerability that was being actively-exploited. The vulnerability was due to type confusion and could be exploited if a victim visited a specially-crafted webpage.

A kernal bug also existed in iPadOS, iOS, and MacOS that could allow an attacker to execute code with kernel privileges.

Nasty stuff. Good idea to update all of the iDevices under your care!

A Few PSAs…

Other Software with Critical Patches Available

Deep Dives

A few interesting deep-dive reads from the month:

Learning – Best Practices for Securing Your Home Network

This month, I’d like to draw your attention to this guide from the NSA: Best Practices for Securing Your Home Network.

It has a lot of great tips, including:

  • Using a non-admin user account for your everyday computer activities.
  • Having your router auto-reboot every week (this will eliminate certain types of malware if they happen to get in).
  • Limiting network admin access to local only (i.e., LAN not WAN).

Take a few minutes to review it and shore up the security of your home network!

Sources & Resources

In addition to inline citations, the following were used or referenced when preparing this debrief.

Thanks for reading, stay safe out there, and have a great weekend! 👩🏽‍💻 🌐 👨🏼‍💻

Written on February 24, 2023 by Alex Smith

At Maxwell, we live our values (ROCKS) everyday. Come tackle worthwhile challenges and make impactful change with us.