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Microsoft Patch Tuesday, December 2023 Edition

By BrianKrebs

The final Patch Tuesday of 2023 is upon us, with Microsoft Corp. today releasing fixes for a relatively small number of security holes in its Windows operating systems and other software. Even more unusual, there are no known “zero-day” threats targeting any of the vulnerabilities in December’s patch batch. Still, four of the updates pushed out today address “critical” vulnerabilities that Microsoft says can be exploited by malware or malcontents to seize complete control over a vulnerable Windows device with little or no help from users.

Among the critical bugs quashed this month is CVE-2023-35628, a weakness present in Windows 10 and later versions, as well as Microsoft Server 2008 and later. Kevin Breen, senior director of threat research at Immersive Labs, said the flaw affects MSHTML, a core component of Windows that is used to render browser-based content. Breen notes that MSHTML also can be found in a number of Microsoft applications, including Office, Outlook, Skype and Teams.

“In the worst-case scenario, Microsoft suggests that simply receiving an email would be enough to trigger the vulnerability and give an attacker code execution on the target machine without any user interaction like opening or interacting with the contents,” Breen said.

Another critical flaw that probably deserves priority patching is CVE-2023-35641, a remote code execution weakness in a built-in Windows feature called the Internet Connection Sharing (ICS) service that lets multiple devices share an Internet connection. While CVE-2023-35641 earned a high vulnerability severity score (a CVSS rating of 8.8), the threat from this flaw may be limited somewhat because an attacker would need to be on the same network as the target. Also, while ICS is present in all versions of Windows since Windows 7, it is not on by default (although some applications may turn it on).

Satnam Narang, senior staff research engineer at Tenable, notes that a number of the non-critical patches released today were identified by Microsoft as “more likely to be exploited.” For example, CVE-2023-35636, which Microsoft says is an information disclosure vulnerability in Outlook. An attacker could exploit this flaw by convincing a potential victim to open a specially crafted file delivered via email or hosted on a malicious website.

Narang said what makes this one stand out is that exploitation of this flaw would lead to the disclosure of NTLM hashes, which could be leveraged as part of an NTLM relay or “pass the hash” attack, which lets an attacker masquerade as a legitimate user without ever having to log in.

”It is reminiscent of CVE-2023-23397, an elevation of privilege vulnerability in Microsoft Outlook that was exploited in the wild as a zero day and patched in the March 2023 Patch Tuesday release,” Narang said. “However, unlike CVE-2023-23397, CVE-2023-35636 is not exploitable via Microsoft’s Preview Pane, which lowers the severity of this flaw.”

As usual, the SANS Internet Storm Center has a good roundup on all of the patches released today and indexed by severity. Windows users, please consider backing up your data and/or imaging your system before applying any updates. And feel free to sound off in the comments if you experience any difficulties as a result of these patches.

When Low-Tech Hacks Cause High-Impact Breaches

By BrianKrebs

Web hosting giant GoDaddy made headlines this month when it disclosed that a multi-year breach allowed intruders to steal company source code, siphon customer and employee login credentials, and foist malware on customer websites. Media coverage understandably focused on GoDaddy’s admission that it suffered three different cyberattacks over as many years at the hands of the same hacking group.  But it’s worth revisiting how this group typically got in to targeted companies: By calling employees and tricking them into navigating to a phishing website.

In a filing with the U.S. Securities and Exchange Commission (SEC), GoDaddy said it determined that the same “sophisticated threat actor group” was responsible for three separate intrusions, including:

-March 2020: A spear-phishing attack on a GoDaddy employee compromised the hosting login credentials of approximately 28,000 GoDaddy customers, as well as login credentials for a small number employees;

-November 2021: A compromised GoDaddy password let attackers steal source code and information tied to 1.2 million customers, including website administrator passwords, sFTP credentials, and private SSL keys;

-December 2022: Hackers gained access to and installed malware on GoDaddy’s cPanel hosting servers that “intermittently redirected random customer websites to malicious sites.”

“Based on our investigation, we believe these incidents are part of a multi-year campaign by a sophisticated threat actor group that, among other things, installed malware on our systems and obtained pieces of code related to some services within GoDaddy,” the company stated in its SEC filing.

What else do we know about the cause of these incidents? We don’t know much about the source of the November 2021 incident, other than GoDaddy’s statement that it involved a compromised password, and that it took about two months for the company to detect the intrusion. GoDaddy has not disclosed the source of the breach in December 2022 that led to malware on some customer websites.

But we do know the March 2020 attack was precipitated by a spear-phishing attack against a GoDaddy employee. GoDaddy described the incident at the time in general terms as a social engineering attack, but one of its customers affected by that March 2020 breach actually spoke to one of the hackers involved.

The hackers were able to change the Domain Name System (DNS) records for the transaction brokering site escrow.com so that it pointed to an address in Malaysia that was host to just a few other domains, including the then brand-new phishing domain servicenow-godaddy[.]com.

The general manager of Escrow.com found himself on the phone with one of the GoDaddy hackers, after someone who claimed they worked at GoDaddy called and said they needed him to authorize some changes to the account.

In reality, the caller had just tricked a GoDaddy employee into giving away their credentials, and he could see from the employee’s account that Escrow.com required a specific security procedure to complete a domain transfer.

The general manager of Escrow.com said he suspected the call was a scam, but decided to play along for about an hour — all the while recording the call and coaxing information out of the scammer.

“This guy had access to the notes, and knew the number to call,” to make changes to the account, the CEO of Escrow.com told KrebsOnSecurity. “He was literally reading off the tickets to the notes of the admin panel inside GoDaddy.”

About halfway through this conversation — after being called out by the general manager as an imposter — the hacker admitted that he was not a GoDaddy employee, and that he was in fact part of a group that enjoyed repeated success with social engineering employees at targeted companies over the phone.

Absent from GoDaddy’s SEC statement is another spate of attacks in November 2020, in which unknown intruders redirected email and web traffic for multiple cryptocurrency services that used GoDaddy in some capacity.

It is possible this incident was not mentioned because it was the work of yet another group of intruders. But in response to questions from KrebsOnSecurity at the time, GoDaddy said that incident also stemmed from a “limited” number of GoDaddy employees falling for a sophisticated social engineering scam.

“As threat actors become increasingly sophisticated and aggressive in their attacks, we are constantly educating employees about new tactics that might be used against them and adopting new security measures to prevent future attacks,” GoDaddy said in a written statement back in 2020.

Voice phishing or “vishing” attacks typically target employees who work remotely. The phishers will usually claim that they’re calling from the employer’s IT department, supposedly to help troubleshoot some issue. The goal is to convince the target to enter their credentials at a website set up by the attackers that mimics the organization’s corporate email or VPN portal.

Experts interviewed for an August 2020 story on a steep rise in successful voice phishing attacks said there are generally at least two people involved in each vishing scam: One who is social engineering the target over the phone, and another co-conspirator who takes any credentials entered at the phishing page — including multi-factor authentication codes shared by the victim — and quickly uses them to log in to the company’s website.

The attackers are usually careful to do nothing with the phishing domain until they are ready to initiate a vishing call to a potential victim. And when the attack or call is complete, they disable the website tied to the domain.

This is key because many domain registrars will only respond to external requests to take down a phishing website if the site is live at the time of the abuse complaint. This tactic also can stymie efforts by companies that focus on identifying newly-registered phishing domains before they can be used for fraud.

A U2F device made by Yubikey.

GoDaddy’s latest SEC filing indicates the company had nearly 7,000 employees as of December 2022. In addition, GoDaddy contracts with another 3,000 people who work full-time for the company via business process outsourcing companies based primarily in India, the Philippines and Colombia.

Many companies now require employees to supply a one-time password — such as one sent via SMS or produced by a mobile authenticator app — in addition to their username and password when logging in to company assets online. But both SMS and app-based codes can be undermined by phishing attacks that simply request this information in addition to the user’s password.

One multifactor option — physical security keys — appears to be immune to these advanced scams. The most commonly used security keys are inexpensive USB-based devices. A security key implements a form of multi-factor authentication known as Universal 2nd Factor (U2F), which allows the user to complete the login process simply by inserting the USB device and pressing a button on the device. The key works without the need for any special software drivers.

The allure of U2F devices for multi-factor authentication is that even if an employee who has enrolled a security key for authentication tries to log in at an impostor site, the company’s systems simply refuse to request the security key if the user isn’t on their employer’s legitimate website, and the login attempt fails. Thus, the second factor cannot be phished, either over the phone or Internet.

In July 2018, Google disclosed that it had not had any of its 85,000+ employees successfully phished on their work-related accounts since early 2017, when it began requiring all employees to use physical security keys in place of one-time codes.

Microsoft Patch Tuesday, December 2022 Edition

By BrianKrebs

Microsoft has released its final monthly batch of security updates for 2022, fixing more than four dozen security holes in its various Windows operating systems and related software. The most pressing patches include a zero-day in a Windows feature that tries to flag malicious files from the Web, a critical bug in PowerShell, and a dangerous flaw in Windows 11 systems that was detailed publicly prior to this week’s Patch Tuesday.

The security updates include patches for Azure, Microsoft Edge, Office, SharePoint Server, SysInternals, and the .NET framework. Six of the update bundles earned Microsoft’s most dire “critical” rating, meaning they fix vulnerabilities that malware or malcontents can use to remotely commandeer an unpatched Windows system — with little to no interaction on the part of the user.

The bug already seeing exploitation is CVE-2022-44698, which allows attackers to bypass the Windows SmartScreen security feature. The vulnerability allows attackers to craft documents that won’t get tagged with Microsoft’s “Mark of the Web,” despite being downloaded from untrusted sites.

“This means no Protected View for Microsoft Office documents, making it easier to get users to do sketchy things like execute malicious macros, said Greg Wiseman, product manager at security firm Rapid7. This is the second Mark of the Web flaw Microsoft has patched in as many months; both were first publicly detailed over the past two months on Twitter by security researcher Will Dormann.

Publicly disclosed (but not actively exploited for now) is CVE-2022-44710, which is an elevation of privilege flaw in the DirectX graphics component of Windows 11.

Another notable critical bug is CVE-2022-41076, a remote code execution flaw in PowerShell — a key component of Windows that makes it easier to automate system tasks and configurations.

Kevin Breen at Immersive Labs said while Microsoft doesn’t share much detail about CVE-2022-41076 apart from the designation ‘Exploitation More Likely,’ they also note that successful exploitation requires an attacker to take additional actions to prepare the target environment.

“What actions are required is not clear; however, we do know that exploitation requires an authenticated user level of access,” Breen said. “This combination suggests that the exploit requires a social engineering element, and would likely be seen in initial infections using attacks like MalDocs or LNK files.”

Speaking of malicious documents, Trend Micro’s Zero Day Initiative highlights CVE-2022-44713, a spoofing vulnerability in Outlook for Mac.

“We don’t often highlight spoofing bugs, but anytime you’re dealing with a spoofing bug in an e-mail client, you should take notice,” ZDI’s Dustin Childs wrote. “This vulnerability could allow an attacker to appear as a trusted user when they should not be. Now combine this with the SmartScreen Mark of the Web bypass and it’s not hard to come up with a scenario where you receive an e-mail that appears to be from your boss with an attachment entitled “Executive_Compensation.xlsx”. There aren’t many who wouldn’t open that file in that scenario.”

Microsoft also released guidance on reports that certain software drivers certified by Microsoft’s Windows Hardware Developer Program were being used maliciously in post-exploitation activity.

Three different companies reported evidence that malicious hackers were using these signed malicious driver files to lay the groundwork for ransomware deployment inside victim organizations. One of those companies, Sophos, published a blog post Tuesday detailing how the activity was tied to the Russian ransomware group Cuba, which has extorted an estimated $60 million from victims since 2019.

Of course, not all scary and pressing security threats are Microsoft-based. Also on Tuesday, Apple released a bevy of security updates to iOS, iPadOS, macOS, tvOS and Safari, including  a patch for a newly discovered zero-day vulnerability that could lead to remote code execution.

Anyone responsible for maintaining Fortinet or Citrix remote access products probably needs to update, as both are dealing with active attacks on just-patched flaws.

For a closer look at the patches released by Microsoft today (indexed by severity and other metrics) check out the always-useful Patch Tuesday roundup from the SANS Internet Storm Center. And it’s not a bad idea to hold off updating for a few days until Microsoft works out any kinks in the updates: AskWoody.com usually has the lowdown on any patches that may be causing problems for Windows users.

As always, please consider backing up your system or at least your important documents and data before applying system updates. And if you run into any problems with these updates, please drop a note about it here in the comments.

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