IT NEWS

In the continued saga of annoying search extensions we have a new end-of-level boss.

Victims have been reporting browser extensions that were removed by Malwarebytes, but “magically” came back later. Since the victims also complained about the message saying their browser was “managed”, we had a pretty good idea where to look.

Search extensions

The culprits turned out to be search extensions. Which is often the case when we spot potentially unwanted programs (PUPs) that use malware tactics to get installed and gain persistence.

The search hijackers “active search bar” and “custom search bar” were both available in the Chrome web store at the time of writing even though we reported them days ago.

PowerShell

It took some digging to find the origin, since all we had were the extensions. And when the extensions were installed directly from the webstore, nothing happened out of the ordinary. However, some hunting on VirusTotal soon led me to a few recently uploaded PowerShell scripts that included the string “ExtensionInstallForcelist.” I looked for that string because we know from the past that these registry policies account for the “Your browser is managed” warnings.

$CPath = "HKLM:SOFTWAREPoliciesGoogleChromeExtensionInstallForcelist";

$EPath = "HKLM:SOFTWAREPoliciesMicrosoftEdgeExtensionInstallForcelist";

The description in the Chromium documentation about the ExtensionInstallForcelist states:

“Specifies a list of apps and extensions that are installed silently, without user interaction, and which cannot be uninstalled nor disabled by the user.”

And to confirm this finding, the victims that provided logs all had one of these PowerShell script listed in their Scheduled Tasks.

The Scheduled Task was set to run every four hours, which explained why the extensions kept coming back.

Installer

But Scheduled Tasks don’t install themselves either and dropping PowerShell scripts in the System32 folder requires Administrator privileges, so we needed to dig a little further to find an installer.

The domain wincloudservice.com was used as a download location in all the PowerShell scripts so we used that domain as a search parameter in our next stage of VirusTotal hunting. This search eventually returned three installers. What they had in common at first glance was that the filenames all ended with “_x64LTS.exe” and that they were all signed by “Tommy Tech LTD.”

Upon further inspection we noticed that the installers all asked for Administrator privileges twice. The first part installs something that is called “Setup” and the second part installs an application that aligns with the name of the installer. So, it appears that the original installer files were “patched” to add the installer for our browser hijacker. It stands to reason that these installers are offered for download somewhere by the threat actors.

The EULA points to tommytechil.com which is unreachable. I was unable to find an installer that actually dropped an extension in Edge, but the “Your browser is managed by your organization” setting does get enforced.

Javascripts

Malwarebytes customers were protected against these extensions as Malwarebytes’ web protection module blocked the domain wincloudservice[.]com. On inspection, this domain hosted several javascripts including heavily obfuscated files called crypto.js and crypto-js.min.js.

Detection and removal

Malwarebytes detects these browser hijackers as PUP.Optional.ActiveSearchBar and PUP.Optional.CustomSearchBar. Included in the removal procedure are the extension, and the Scheduled Task, which is enough to permanently get rid of the extension.

Some Windows registry changes have been made that will take a system administrator to decide what they want to keep or not.

The registry keys to remove the “Your browser is managed” are:

HKEY_LOCAL_MACHINESOFTWAREPoliciesGoogleChromeExtensionInstallForceList

HKEY_LOCAL_MACHINESOFTWAREPoliciesMicrosoftEdgeExtensionInstallForceList

And another change made by the installer was the registry value:

HKEY_LOCAL_MACHINESOFTWAREMicrosoftPowerShell1ShellIdsMicrosoft.PowerShell\ExecutionPolicy

The installer set that to “Unrestricted” which may not be your favorite setting. If you are not sure or you have never actively set that policy, the default is “Restricted”. Please note that in some organizations PowerShell is required to run.

IOCs

Domains:

activesearchbar[.]me

customsearchbar[.]me

optimizerupdate[.]com

securedatacorner[.]com

wincloudservice[.]com

Installers:

4kvideodownloader_5.22.371_x64LTS.exe

AutoClicker_x64LTS.exe

FPSUnlocker_4.1_x64LTS.exe

PowerShell scripts:

PrintWorkflowService.ps1

WindowsUpdater1.ps1

OptimizerWindows.ps1

Extensions:

custom search bar nniikbbaboifhfjjkjekiamnfpkdieng

active search bar pkofdnfadkamabkgjdjcddeopopbdjhg

The post Forced Chrome extensions get removed, keep reappearing appeared first on Malwarebytes Labs.

A person working in the city of Amagasaki, in Western Japan, has mislaid a USB stick which contained data on the city’s 460,000 residents.

The USB drive was in a bag that went missing during a reported day of drinking and dining at a restaurant last Tuesday. The person reported it to the police the following day.

Data on the USB drive included names, gender, birthdays, and addresses. Other additional personal details were included, though it’s not been revealed what this is. Bank account numbers of households receiving welfare also found themselves on the USB drive.

Safety first pays dividends

The one piece of good news to emerge from this story is that the drive was both encrypted and password protected. So, providing they used a good password, if someone finds the USB drive and plugs it into a computer, they won’t be able to just open up the files and view the contents.

If whoever put this drive together hadn’t bothered with security measures, the first person to find the lost drive would have a data payday on their hands. Perhaps as a result of this cautious approach, there’s been no evidence or reports of the data being leaked so far.

How to safely transfer data

There is the question of why this data was on a USB stick in the first place. According to CBSNews, it was being transferred to a call center in Osaka. There are plenty of alternatives to ferrying data around on easily lost USB sticks. While some industries have strict compliance and regulatory standards, others may simply not be able to use third-party products for a variety of reasons. Even so, anything along these lines is surely better than “I lost a USB stick on a night out”. With this caveat out of the way:

• Secure File Transfer Protocol (SFTP). This is used in business as a way to securely send files from one device to another. Files sent using this method are done so via an encrypted connection. One potential drawback here is you’ll likely need software installed on all the machines receiving the files. If you need to send data to another organisation, this can quickly become complicated or unfeasible. Additionally, not everyone believes it’s a suitable option for secure file transfer when more custom-built solutions are now available.
• Data in the cloud. Third party cloud products like Dropbox and Box allow you to store, and share, files. They both have lots to offer, with Box in particular being specifically geared towards business solutions. Multi-factor authentication, malware detection and leak prevention, encryption and compliance: it’s all there. Services like the above are increasingly more popular in business circles where secure, pain-free data transfer is required but the in-house knowledge required to do it yourself isn’t to hand.
• Encrypting your data and your USB drive. In some situations it may well be “USB drive or nothing at all”. If you’re using Windows 10 Home, you’ll need to use a third-party solution to encrypt files as the option will be greyed out. If you’re on other versions like Pro and Enterprise, the encryption option will be available to you. Right click your file(s), then select Properties -> Advanced -> Encrypt contents to secure data. As for the drive itself, you’ll once again have to rely on third-party tools if you’re running Windows 10 Home. Otherwise, you can secure the drive with Bitlocker. Mac users should select the Encrypt USB stick option from the location entry, then create and verify the encryption password. Be sure to set a password hint, too. Hit Encrypt Disk to complete the process.

The post City worker loses USB stick containing data on every resident after day of drinking appeared first on Malwarebytes Labs.

The FTC (Federal Trade Commission) has warned the LGBTQ+ community about extortionists posing as potential romantic partners on Grindr and Feeld.

The scammers send their targets explicit photos and then ask for them to reciprocate. If they do, targets are then blackmailed into paying a ransom, usually in the form of gift cards, or risk having these photos leaked to family, friends, and employers.

And that’s not all, the scammers are also looking to out people, unless they pay a ransom. According to the FTC:

“Other scammers threaten people who are “closeted” or not yet fully “out” as LGBTQ+. They may pressure you to pay up or be outed, claiming they’ll “ruin your life” by exposing explicit photos or conversations.”

How to protect yourself from extortionists

• Always check who you’re talking to. Do is a reverse image search of their profile photo to see what shows up. If the name doesn’t match up with the face, end communications promptly, and report the account to the dating app/site.
• Be careful about sending compromising images of yourself to someone. Trust your gut. Realize that extortionists are after such photos to use them as bargaining chips.
• Never send your personal information. This includes email addresses, social media profiles, and smartphone numbers.
• Avoid opening attachments or clicking links. They may contain malware designed to hijack devices or steal your information.
• Disable your webcam and electronic devices when not in use.
• Never pay the ransom. Scammers are known for promising one thing and doing the other. Remember that if you pay them, there’s no guarantee they’ll keep their word.
• Report it to the FBI and FTC. Don’t wait to be in deep with the scammer. Once you smell fraud, cease communications immediately and report.

Grindr and Feeld also have helpful guides for their users.

Stay safe!

The post LGBTQ+ community targeted by extortionists who threaten to publish nudes appeared first on Malwarebytes Labs.

Last week on Malwarebytes Labs:

• LinkedIn scams are a “significant threat”, warns FBI
• DDoS-for-hire service provider jailed
• Internet Safety Month: 7 tips for staying safe online while on vacation
• Client-side Magecart attacks still around, but more covert
• Security vulnerabilities: 5 times that organizations got hacked
• You can be tracked online using your Chrome browser extensions
• Russia’s APT28 uses fear of nuclear war to spread Follina docs in Ukraine
• DFSCoerce, a new NTLM relay attack, can take control over a Windows domain
• Watch out for the email that says “You have a new voicemail!”
• 7-Zip gets Mark of the Web feature, increases protection for users
• MEGA claims it can’t decrypt your files. But someone’s managed to…
• Police seize and dismantle massive phishing operation
• Rogue cryptocurrency billboards go phishing for wallets
• Dial 311 for…cybersecurity emergencies?
• Conti ransomware group’s pulse stops, but did it fake its own death?
• Cybersecurity agencies: You don’t have to delete PowerShell to secure it
• 5 ways to avoid being catfished

Stay safe!

The post A week in security (June 20 – June 26) appeared first on Malwarebytes Labs.

If Instagram suspects you are fibbing about your age, you’ll currently see the following message:

“You must be at least 13 years old to have an Instagram account. We disabled your account because you are not old enough yet. If you believe we made a mistake, please verify your age by submitting a valid photo ID that clearly shows your face and date of birth.”

Now Meta has announced it’s testing new options for people on Instagram to verify their age, starting with people in the US. The new options are uploading a video selfie, and social vouching. The old verification method to upload an ID is still an option for those that prefer it.

Users that are unable to verify their age will have their accounts deleted.

Trigger

The verification procedure starts when a user attempts to raise their age from under to above 18. This is relevant since Instagram provides users from 13 -17 years old with age-appropriate experiences like defaulting them into private accounts, preventing unwanted contact from adults they don’t know, and limiting the options advertisers have to reach them with ads.

Other reasons Instagram might ask you to verify your age are it receives a report from another Instagram user, or a content reviewers flags your accounts as appearing to be in use by someone underage.

Social vouching

The social vouching option allows you to ask mutual followers to confirm how old you are. You might expect this to be an option that can easily be abused, but Meta says it’s built in additional safeguards. Three people must independently confirm the user is over 18, and they all must be at least 18 years old themselves and not be vouching for anyone else at that time.

Video selfie

Certainly the option that raises some concerns is the video selfie. You can choose to upload a video selfie to verify your age. If you choose this option, you’ll see instructions on your screen to guide you through the process. The age analysis, an estimate of your age based on your facial features, is done by Yoti, and both Meta and Yoti promise to delete the image once the analysis has completed.

You may have heard of Yoti due to its digital ID app. Yoti is a free consumer app that offers you a way of proving who you are online and in person. In the UK, Yoti is a government-approved digital ID provider, which allows UK citizens to prove their identities with an app instead of physical documents when applying for a job or renting a property.

Additional AI usage

In addition to testing the new menu of options to verify people’s ages, Meta uses Artificial Intelligence to estimate people’s ages. This can be very simple indicators, like birthday wishes, or comparing the age of linked accounts, such as your Facebook and Instagram accounts. But it can also look at interactions with other profiles and content. For example, people in the same age group tend to interact similarly with certain types of content. From those signals, the model learns to make calculations about whether someone is an adult or a teen.

The post Instagram introduces new ways for users to verify their age appeared first on Malwarebytes Labs.

CISA and the United States Coast Guard Cyber Command (CGCYBER) are warning that the threat of Log4Shell hasn’t gone away. It’s being actively exploited and used to target organisations using VMware Horizon and Unified Access Gateway servers.

Log4Shell: what is it?

Log4Shell was a zero-day vulnerability in something called Log4j. This open source logging library written in Java is used by millions of applications, many of them incredibly popular. The easy to trigger attack could be used to perform remote code execution (RCE) on vulnerable systems. If successful, attackers could gain full control over a target system. If they managed to have affected apps log a special string, then it was a case of game over. The system(s) at this point would be ripe for exploitation.

Discovered in November 2021, the exploit was estimated to potentially affect hundreds of millions of devices. With so much potential for damage, fixes were quickly developed and released on December 6, three days before the vulnerability was published.

Related bugs and additional vulnerabilities were also discovered and subsequently patched.

Broadening Log4Shell’s horizons

According to CISA and CGCYBER, Log4Shell has been used to exploit unpatched, public-facing VMWare Horizon and UAG servers. Suspected APT threat actors…

…implanted loader malware on compromised systems with embedded executables enabling remote command and control (C2). In one confirmed compromise, these APT actors were able to move laterally inside the network, gain access to a disaster recovery network, and collect and exfiltrate sensitive data.

Attackers not only make use of malware and HTTP, but also PowerShell scripts and Remote Desktop Protocol (RDP). In the latter’s case, this was to further move around the network and other hosts inside the organisation’s production environment.

Compromised administrator accounts were used to run several additional forms of loader malware. Here are some of the samples found by CISA during one investigation:

• SvcEdge.exe is a malicious Windows loader containing encrypted executable f7_dump_64.exe. When executed, SvcEdge.exe decrypts and loads f7_dump_64.exe into memory.
• odbccads.exe is a malicious Windows loader containing an encrypted executable. When executed, odbccads.exe decrypts and loads the executable into memory.
• praiser.exe is a Windows loader containing an encrypted executable. When executed, praiser.exe decrypts and loads the executable into memory.
• fontdrvhosts.exe is a Windows loader that contains an encrypted executable. When executed, fontdrvhosts.exe decrypts and loads the executable into memory.
• winds.exe is a Windows loader containing an encrypted malicious executable and was found on a server running as a service. During runtime, the encrypted executable is decrypted and loaded into memory. winds.exe has complex obfuscation, hindering the analysis of its code structures.

Advice for securing installations

CISA/CGCYBER are quite clear about this. Organisations which haven’t applied patches released back in December should treat any and all affected VMware systems as compromised:

• Install fixed builds, updating all affected VMware Horizon and UAG systems to the latest versions. If updates or workarounds were not promptly applied following VMware’s release of updates for Log4Shell in December 2021, treat all affected VMware systems as compromised.
• Minimize the internet-facing attack surface by hosting essential services on a segregated demilitarized (DMZ) zone, ensuring strict network perimeter access controls, and implementing regularly updated web application firewalls (WAFs) in front of public-facing services.
• See VMware Security Advisory VMSA-2021-0028.13 and VMware Knowledge Base (KB) 87073 to determine which VMware Horizon components are vulnerable.
• Note: Until the update is fully implemented, consider removing vulnerable components from the internet to limit the scope of traffic. While installing the updates, ensure network perimeter access controls are as restrictive as possible.
• If upgrading is not immediately feasible, see KB87073 and KB87092 for vendor-provided temporary workarounds. Implement temporary solutions using an account with administrative privileges. Note that these temporary solutions should not be treated as permanent fixes; vulnerable components should be upgraded to the latest build as soon as possible. 
• Prior to implementing any temporary solution, ensure appropriate backups have been completed. 
• Verify successful implementation of mitigations by executing the vendor supplied script Horizon_Windows_Log4j_Mitigations.zip without parameters to ensure that no vulnerabilities remain. See KB87073 for details. 

Log4Shell, rated a 10 in the Common Vulnerability Scoring System (CVSS), is not to be trifled with. We advise affected organisations to pay heed to the warnings above and set about patching as soon as possible.

The post CISA Log4Shell warning: Patch VMware Horizon installations immediately appeared first on Malwarebytes Labs.

Brave Search, Brave Software’s privacy search engine, just turned one. To celebrate, the company says it is moving the search engine out of its beta phase to become the default search engine for all Brave browser users.

Goodbye, Google? Not entirely.

In May 2015, Mozilla alumni Brendan Eich and Brian Bondy launched Brave Software. Its first product was the Brave Browser, a privacy-friendly, Chromium-based internet browser that automatically blocks ads and site trackers. In March 2021, the company launched Brave Search so it could use its own index to generate search results.

In a recent announcement, the company said its search engine had passed 2.5 billion queries since its release a year earlier. That was a staggering increase in a year, from 8.1 million search queries to 411.7M by May 2022. However, as impressive as that is, Brave Search (and the other privacy search engine, DuckDuckGo) are still lightyears away from challenging Google’s hegemony. While Google enjoys a 92% market share, Brave has yet to break out of the search engine ranking’s miniscule “other” category.

Besides a loyal following, one reason for Brave Search’s fast growth is likely that it (mostly) avoids using third-party search indexes, such as Google and Bing. According to Brave’s blog, 92 percent of queries users receive are directly from Brave’s search index. The company admitted, however, that they will be pulling search results from other providers—Google in particular—if their index doesn’t have enough data of its own.

Search engines that depend too much, or exclusively, on Big Tech are subject to their censorship, biases, and editorial decisions. The Web needs multiple search providers—without choice there’s no freedom.

Brave’s blog

Brave Search is currently ad-free, but the company has plans to work on an ad-supported version of Search. This will involve Brave Ads, Brave’s adtech platform. Users who click these ads are rewarded 70 percent of the ad revenue.

While Brave is quick to claim that its query algorithms are unbiased, The Verge pointed out that all algorithms have inherent biases. But Goggles, a new feature, may help to mitigate this.

Going gaga over Goggles

Brave also announced a new Brave Search results curation feature called “Goggles,” which interested users can start testing out right now. The company has already prepared some demos to try.

“Goggles will enable anyone, or any community of people, to create sets of rules and filters to constrain the searchable space and / or alter the ordering of search results,” the browser company explains. “Essentially, Goggles will act as a re-ranking option on top of the Brave Search index.”

The search team released a white paper on Goggles, detailing its features and showcasing how these work using examples. In a nutshell, Brave is giving its users access to information filtered by their own explicit biases. This means that users’ preferences take precedence over Brave’s preferences.

Brave presented benefits for both the average user and content creator:

“The benefit for the users is that they would be empowered to explore multiple realities in a straight-forward way. The point is to offer people the freedom to choose their own biases while being conscious of them.”

“The benefit for the content creators is that they have multiple options to expose their content, by increasing their potential audience, which will reduce the need to optimize for the single set of biases implicitly encoded in the search engine’s ranking.”

The only downside to Goggles, so far, is that it’s not as easy to use as you might think. You can’t simply enter keywords or personalize preset filters. There is some coding involved, which might put off users without coding experience.

In addition to Goggles, Brave also released Discussions in April. This is a way to augment Brave Search results with actual conversations pulled from popular sites, all related to the search query.

The post Brave Search wants to replace Google’s biased search results with yours appeared first on Malwarebytes Labs.

Microsoft has posted a reminder that Exchange Server 2013 reaches End of Support (EoS) on April 11, 2023.  That’s a little more than 9 months from now. A useful and timely reminder, since we all realize that it takes some time to migrate to a different system.

Every Windows product has a lifecycle. The lifecycle begins when a product is released and ends when it’s no longer supported. Knowing key dates in this lifecycle helps you make informed decisions about when to update, upgrade, or make other changes to your software.

Exchange Server

Microsoft Exchange Server is a groupware solution platform that provides many organizations with a mail server and calendaring server. It runs exclusively on Windows Server operating systems.

A few weeks ago Microsoft announced that the 2021 subscription model version of Exchange Server was not going to happen. So there may have been some questions whether the EoS for Exchange Server 2013 would go forward as planned. Now we know the answer: Yes.

Since the next on-premise version is not expected until the second half of 2025, your upgrade options are Exchange Server 2016 and Exchange Server 2019. Unless you want to migrate to the Exchange Online version.

End of Support

EoS (also called End-of-Life, or EoL) describes the final stage of a product’s lifecycle. Once a product reaches EoS, developers stop creating updates and patches for the product.

For Exchange Server 2013 this means that Microsoft will no longer provide:

• Technical support for problems that may occur.
• Fixes for usability or stability bugs.
• Time zone updates.
• Security fixes.

EoS makes the most basic security hygiene practice, “patch now”, impossible, and vulnerabilities discovered after EoS remain an open wound forever.

Immediate threats

Microsoft has chosen to further develop Exchange Server 2019, rather than come out with a completely new version. It mentioned the fact that state sponsored threat actors, like Hafnium, are targeting on-premises Exchange servers as one of the reasons for the cancellation of Exchange Server 2021.

The number and severity of active threats that target Exchange Server is worrying enough. And this will only get worse when one of the versions is no longer eligible for bug and security fixes.

The most prominent threats for Exchange Servers from last year were:

• ProxyLogon that was used to infect thousands of servers before Microsoft released patches. targets on-premise Exchange servers.
• ProxyOracle is a bit less numerous since threat actors have to trick users into clicking on a malicious link to steal the user’s password.
• ProxyToken allows an unauthenticated attacker to perform configuration actions on mailboxes belonging to arbitrary users.
• ProxyShell another on-premise Exchange Server vulnerability on unpatched servers with Internet access.

By now, all of the above have had patches created for them. Unfortunately that doesn’t mean that all vulnerable Exchange Servers have installed the relevant updates. But new vulnerabilities will be found. And vulnerabilities that work on a server software that no longer receives patches will be critical.

Transition

If you don’t want to get stuck with an unpatchable Exchange Server version, it is time to start planning, find the necessary budget, maybe think through what you are going to use next, and when is the best time for the transition.

Stay safe, everyone!

The post You only have nine months to ditch Exchange Server 2013 appeared first on Malwarebytes Labs.

Today, many Americans will head out to the water—not to swim, but to catch a catfish in time for National Catfish Day.

But when we talk about catfishing in cybersecurity, we mean something different. Here, catfishing refers to someone who assumes someone else’s identity online in order to harass, troll, or scam someone.

But there are ways to protect yourself:

1. Be suspicious

Catfishes and romance scammers prowl social media sites and dating apps.

Usually, scammers will message potential targets privately first, through DMs. And when the target bites, they immediately ask them to switch to a more private chat option, such as email or text.

If you suspect you are being catfished, ask them questions that only someone with their background would know. If they’re hesitant, slow to answer, or try to avoid your questions, then be wary.

2. Don’t fall too quickly for a pretty face

Scammers know that people are likely to respond positively if they’re using an image of someone who looks good. But you can use that pretty picture for your own benefit. Do a reverse-image search to check if the face matches the name, or if anyone has mentioned scams alongside that image.

Take note, though, that scammers can entirely steal the identity of someone and use it. They can also use create a deepfake image, which wouldn’t be caught in reverse-image searches.

3. Take it slow

If a love interest ticks all your boxes, remind yourself to slow down. Scammers will want to get you moving, so they can go on to target someone else.

And, since scammers talk to multiple targets, they can make big mistakes, such as forgetting your or their name. Taking it slow may not seem to be the most exciting thing you’d do, but it gives you a chance to build up a bigger picture of the person you are talking to.

4. Talk to someone you trust

An outsider perspective is invaluable if you’re about to fall head first for a scammer.

Let’s face it, sometimes we see the red flags but choose to ignore them. A second or third opinion from someone you trust might be the jolt you need before it’s too late.

5. Never send them anything

Scammers are quick about everything regarding love, revealing too much about “their personal life,” professing their love, or asking something from you. That could be money, cryptocurrency, personal information, banking details, or gift card numbers.

Occasionally, they might ask you to move money on their behalf. Never do this, even if it sounds like they are desperate for your help.

Finally

If you suspect someone is a scammer, immediately stop contact and report them to the site where you first met, whether that was on social media or a dating app. If you have mistakenly sent someone money, file a report to your bank ASAP. And don’t hesitate to report your experience to your local law enforcement and FBI office.

Stay safe!

The post 5 ways to avoid being catfished appeared first on Malwarebytes Labs.

Microsoft’s PowerShell is a useful, flexible tool that is as popular with criminals as it is with admins. Cybercrooks like it becasue PowerShell is powerful, available almost everywhere, and doesn’t look out of place running on a company network.

In most places it isn’t practical to block PowerShell completely, which raises the question: How do you stop the bad stuff without disrupting the good stuff?

Cybersecurity authorities from the United States, New Zealand, and the United Kingdom have released a joint Cybersecurity Information Sheet (CIS) on PowerShell that attempts to answer that question.

The National Security Agency (NSA), the Cybersecurity and Infrastructure Security Agency (CISA), the New Zealand National Cyber Security Centre (NZ NCSC), and the United Kingdom National Cyber Security Centre (NCSC-UK) hope that “these recommendations will help defenders detect and prevent abuse by threat actors, while enabling legitimate use by administrators and defenders.”

PowerShell

Although it’s closely associated with the world of Windows administration, PowerShell is a cross-platform (Windows, Linux, and macOS) automation and configuration tool which, by design, is optimized for dealing with structured data. Initially a Windows component only, known as Windows PowerShell, it was made open-source and cross-platform on 18 August 2016 with the introduction of PowerShell Core.

It allows system administrators and power users to perform administrative tasks via a command line—an area where Windows previously lagged behind its Unix-like rivals with their proliferation of *sh shells.

Threat actors are equally fond of it because it allows them to “live off the land”, and for the options it provides to create fileless malware or to gain persistence on a compromised system.

Reduce abuse

The CIS discusses some security features available in PowerShell which can reduce abuse by threat actors.

Remote connections

Remote connections can be used for powerful remote management capabilities, so Windows Firewall rules on endpoints should be configured appropriately to control permitted connections. Access to endpoints with PowerShell remoting requires the requesting user account to have administrative privileges at the destination by default. The permission requirement and Windows Firewall rules are customizable for restricting connections to only trusted endpoints and networks to reduce lateral movement opportunities. Organizations can implement these rules to harden network security where feasible.

Multiple authentication methods in PowerShell permit use on non-Windows devices. PowerShell 7 permits remote connections over Secure Shell (SSH) in addition to supporting Windows Remote Management (WinRM) connections. This allows for public key authentication and makes remote management through PowerShell of machines more convenient and secure.

AMSI integration

The Antimalware Scan Interface (AMSI) feature, first available on Windows 10, is integrated into different Windows components. It supports scanning of in-memory and dynamic file contents using an anti-malware product registered with Windows and exposes an interface for applications to scan potentially malicious content. This feature requires AMSI-aware anti-malware products (such as Malwarebytes). Basically, AMSI works by analyzing scripts before the execution, so the anti-malware product can determine if the script is malicious or not.

Constrained Language Mode

Configuring AppLocker or Windows Defender Application Control (WDAC) to block actions on a Windows host will cause PowerShell to operate in Constrained Language Mode (CLM), restricting PowerShell operations unless allowed by administrator-defined policies.

PowerShell methods to detect abuse

Logging of PowerShell activities can record when cyber threats use PowerShell, and continuous monitoring of PowerShell logs can detect and alert on potential abuses. Deep Script Block Logging, Module Logging, and Over-the-Shoulder transcription are disabled by default. The authors recommend enabling the capabilities where feasible.

Before you start

If you plan on following the advice in the CIS, there are a few things you may want to consider first.

• Execution Policies do not restrict execution of all PowerShell content.
• AMSI bypasses are found and remediated in a constant whack-a-mole game, and most anti-malware products have different ways of accomplishing the same, or better, results. Therefor you will find that most AMSI-aware anti-malware products do not rely on AMSI alone.
• If you are a customer of a Managed Service Provider (MSP) you may need to contact them before taking any of the actions listed above, since doing so may hinder them in their remote management.
• Windows Remote Management/Remote Shell (WinRM/WinRS) connection limitations can become an obstacle in organizations with numerous administrators performing remote management, or that have multiple monitoring solutions connecting to the environment. By default, Microsoft Server limits the number of concurrent users connected to the WinRM/WinRS session to five and the number of shells per user to five. This can, and has often been modified by using an elevated command prompt.

Disabling PowerShell, if you do not need it, is a lot easier and safer than applying policies to make it safer to use. But looking at the options to make it more secure is certainly a good idea if you do need it.

Stay safe, everyone!

The post Cybersecurity agencies: You don’t have to delete PowerShell to secure it appeared first on Malwarebytes Labs.