Time to Patch


12
Jan 21

Microsoft Patch Tuesday, January 2021 Edition

Microsoft today released updates to plug more than 80 security holes in its Windows operating systems and other software, including one that is actively being exploited and another which was disclosed prior to today. Ten of the flaws earned Microsoft’s most-dire “critical” rating, meaning they could be exploited by malware or miscreants to seize remote control over unpatched systems with little or no interaction from Windows users.

Most concerning of this month’s batch is probably a critical bug (CVE-2021-1647) in Microsoft’s default anti-malware suite — Windows Defender — that is seeing active exploitation. Microsoft recently stopped providing a great deal of detail in their vulnerability advisories, so it’s not entirely clear how this is being exploited.

But Kevin Breen, director of research at Immersive Labs, says depending on the vector the flaw could be trivial to exploit.

“It could be as simple as sending a file,” he said. “The user doesn’t need to interact with anything, as Defender will access it as soon as it is placed on the system.”

Fortunately, this bug is probably already patched by Microsoft on end-user systems, as the company continuously updates Defender outside of the normal monthly patch cycle.

Breen called attention to another critical vulnerability this month — CVE-2020-1660 — which is a remote code execution flaw in nearly every version of Windows that earned a CVSS score of 8.8 (10 is the most dangerous).

“They classify this vulnerability as ‘low’ in complexity, meaning an attack could be easy to reproduce,” Breen said. “However, they also note that it’s ‘less likely’ to be exploited, which seems counterintuitive. Without full context of this vulnerability, we have to rely on Microsoft to make the decision for us.” Continue reading →


8
Dec 20

Patch Tuesday, Good Riddance 2020 Edition

Microsoft today issued its final batch of security updates for Windows PCs in 2020, ending the year with a relatively light patch load. Nine of the 58 security vulnerabilities addressed this month earned Microsoft’s most-dire “critical” label, meaning they can be abused by malware or miscreants to seize remote control over PCs without any help from users.

Mercifully, it does not appear that any of the flaws fixed this month are being actively exploited, nor have any them been detailed publicly prior to today.

The critical bits reside in updates for Microsoft Exchange Server, Sharepoint Server, and Windows 10 and Server 2016 systems. Additionally, Microsoft released an advisory on how to minimize the risk from a DNS spoofing weakness in Windows Server 2008 through 2019.

Some of the sub-critical “important” flaws addressed this month also probably deserve prompt patching in enterprise environments, including a trio of updates tackling security issues with Microsoft Office.

“Given the speed with which attackers often weaponize Microsoft Office vulnerabilities, these should be prioritized in patching,” said Allan Liska, senior security architect at Recorded Future. “The vulnerabilities, if exploited, would allow an attacker to execute arbitrary code on a victim’s machine. These vulnerabilities affect Microsoft Excel 2013 through 2019, Microsoft 365 32 and 64 bit versions, Microsoft Office 2019 32 and 64 bit versions, and Microsoft Excel for Mac 2019.”

We also learned this week that Redmond quietly addressed a scary “zero-click” vulnerability in its Microsoft Teams platform that would have let anyone execute code of their choosing just by sending the target a specially-crafted chat message to a Teams users. The bug was cross-platform, meaning it could also have been used to deliver malicious code to people using Teams on non-Windows devices. Continue reading →


10
Nov 20

Patch Tuesday, November 2020 Edition

Adobe and Microsoft each issued a bevy of updates today to plug critical security holes in their software. Microsoft’s release includes fixes for 112 separate flaws, including one zero-day vulnerability that is already being exploited to attack Windows users. Microsoft also is taking flak for changing its security advisories and limiting the amount of information disclosed about each bug.

Some 17 of the 112 issues fixed in today’s patch batch involve “critical” problems in Windows, or those that can be exploited by malware or malcontents to seize complete, remote control over a vulnerable Windows computer without any help from users.

Most of the rest were assigned the rating “important,” which in Redmond parlance refers to a vulnerability whose exploitation could “compromise the confidentiality, integrity, or availability of user data, or of the integrity or availability of processing resources.”

A chief concern among all these updates this month is CVE-2020-17087, which is an “important” bug in the Windows kernel that is already seeing active exploitation. CVE-2020-17087 is not listed as critical because it’s what’s known as a privilege escalation flaw that would allow an attacker who has already compromised a less powerful user account on a system to gain administrative control. In essence, it would have to be chained with another exploit.

Unfortunately, this is exactly what Google researchers described witnessing recently. On Oct. 20, Google released an update for its Chrome browser which fixed a bug (CVE-2020-15999) that was seen being used in conjunction with CVE-2020-17087 to compromise Windows users.

If you take a look at the advisory Microsoft released today for CVE-2020-17087 (or any others from today’s batch), you might notice they look a bit more sparse. That’s because Microsoft has opted to restructure those advisories around the Common Vulnerability Scoring System (CVSS) format to more closely align the format of the advisories with that of other major software vendors.

But in so doing, Microsoft has also removed some useful information, such as the description explaining in broad terms the scope of the vulnerability, how it can be exploited, and what the result of the exploitation might be. Microsoft explained its reasoning behind this shift in a blog post.

Not everyone is happy with the new format. Bob Huber, chief security officer at Tenable, praised Microsoft for adopting an industry standard, but said the company should consider that folks who review Patch Tuesday releases aren’t security practitioners but rather IT counterparts responsible for actually applying the updates who often aren’t able (and shouldn’t have to) decipher raw CVSS data.

“With this new format, end users are completely blind to how a particular CVE impacts them,” Huber said. “What’s more, this makes it nearly impossible to determine the urgency of a given patch. It’s difficult to understand the benefits to end-users. However, it’s not too difficult to see how this new format benefits bad actors. They’ll reverse engineer the patches and, by Microsoft not being explicit about vulnerability details, the advantage goes to attackers, not defenders. Without the proper context for these CVEs, it becomes increasingly difficult for defenders to prioritize their remediation efforts.” Continue reading →


13
Oct 20

Microsoft Patch Tuesday, October 2020 Edition

It’s Cybersecurity Awareness Month! In keeping with that theme, if you (ab)use Microsoft Windows computers you should be aware the company shipped a bevy of software updates today to fix at least 87 security problems in Windows and programs that run on top of the operating system. That means it’s once again time to backup and patch up.

Eleven of the vulnerabilities earned Microsoft’s most-dire “critical” rating, which means bad guys or malware could use them to gain complete control over an unpatched system with little or no help from users.

Worst in terms of outright scariness is probably CVE-2020-16898, which is a nasty bug in Windows 10 and Windows Server 2019 that could be abused to install malware just by sending a malformed packet of data at a vulnerable system. CVE-2020-16898 earned a CVSS Score of 9.8 (10 is the most awful).

Security vendor McAfee has dubbed the flaw “Bad Neighbor,” and in a blog post about it said a proof-of-concept exploit shared by Microsoft with its partners appears to be “both extremely simple and perfectly reliable,” noting that this sucker is imminently “wormable” — i.e. capable of being weaponized into a threat that spreads very quickly within networks.

“It results in an immediate BSOD (Blue Screen of Death), but more so, indicates the likelihood of exploitation for those who can manage to bypass Windows 10 and Windows Server 2019 mitigations,” McAfee’s Steve Povolny wrote. “The effects of an exploit that would grant remote code execution would be widespread and highly impactful, as this type of bug could be made wormable.”

Trend Micro’s Zero Day Initiative (ZDI) calls special attention to another critical bug quashed in this month’s patch batch: CVE-2020-16947, which is a problem with Microsoft Outlook that could result in malware being loaded onto a system just by previewing a malicious email in Outlook.

“The Preview Pane is an attack vector here, so you don’t even need to open the mail to be impacted,” said ZDI’s Dustin Childs.

While there don’t appear to be any zero-day flaws in October’s release from Microsoft, Todd Schell from Ivanti points out that a half-dozen of these flaws were publicly disclosed prior to today, meaning bad guys have had a jump start on being able to research and engineer working exploits. Continue reading →


8
Sep 20

Microsoft Patch Tuesday, Sept. 2020 Edition

Microsoft today released updates to remedy nearly 130 security vulnerabilities in its Windows operating system and supported software. None of the flaws are known to be currently under active exploitation, but 23 of them could be exploited by malware or malcontents to seize complete control of Windows computers with little or no help from users.

The majority of the most dangerous or “critical” bugs deal with issues in Microsoft’s various Windows operating systems and its web browsers, Internet Explorer and Edge. September marks the seventh month in a row Microsoft has shipped fixes for more than 100 flaws in its products, and the fourth month in a row that it fixed more than 120.

Among the chief concerns for enterprises this month is CVE-2020-16875, which involves a critical flaw in the email software Microsoft Exchange Server 2016 and 2019. An attacker could leverage the Exchange bug to run code of his choosing just by sending a booby-trapped email to a vulnerable Exchange server.

“That doesn’t quite make it wormable, but it’s about the worst-case scenario for Exchange servers,” said Dustin Childs, of Trend Micro’s Zero Day Initiative. “We have seen the previously patched Exchange bug CVE-2020-0688 used in the wild, and that requires authentication. We’ll likely see this one in the wild soon. This should be your top priority.”

Also not great for companies to have around is CVE-2020-1210, which is a remote code execution flaw in supported versions of Microsoft Sharepoint document management software that bad guys could attack by uploading a file to a vulnerable Sharepoint site. Security firm Tenable notes that this bug is reminiscent of CVE-2019-0604, another Sharepoint problem that’s been exploited for cybercriminal gains since April 2019.

Microsoft fixed at least five other serious bugs in Sharepoint versions 2010 through 2019 that also could be used to compromise systems running this software. And because ransomware purveyors have a history of seizing upon Sharepoint flaws to wreak havoc inside enterprises, companies should definitely prioritize deployment of these fixes, says Alan Liska, senior security architect at Recorded Future. Continue reading →


17
Aug 20

Microsoft Put Off Fixing Zero Day for 2 Years

A security flaw in the way Microsoft Windows guards users against malicious files was actively exploited in malware attacks for two years before last week, when Microsoft finally issued a software update to correct the problem.

One of the 120 security holes Microsoft fixed on Aug. 11’s Patch Tuesday was CVE-2020-1464, a problem with the way every supported version of Windows validates digital signatures for computer programs.

Code signing is the method of using a certificate-based digital signature to sign executable files and scripts in order to verify the author’s identity and ensure that the code has not been changed or corrupted since it was signed by the author.

Microsoft said an attacker could use this “spoofing vulnerability” to bypass security features intended to prevent improperly signed files from being loaded. Microsoft’s advisory makes no mention of security researchers having told the company about the flaw, which Microsoft acknowledged was actively being exploited.

In fact, CVE-2020-1464 was first spotted in attacks used in the wild back in August 2018. And several researchers informed Microsoft about the weakness over the past 18 months.

Bernardo Quintero is the manager at VirusTotal, a service owned by Google that scans any submitted files against dozens of antivirus services and displays the results. On Jan. 15, 2019, Quintero published a blog post outlining how Windows keeps the Authenticode signature valid after appending any content to the end of Windows Installer files (those ending in .MSI) signed by any software developer.

Quintero said this weakness would be particularly acute if an attacker were to use it to hide a malicious Java file (.jar). And, he said, this exact attack vector was indeed detected in a malware sample sent to VirusTotal.

“In short, an attacker can append a malicious JAR to a MSI file signed by a trusted software developer (like Microsoft Corporation, Google Inc. or any other well-known developer), and the resulting file can be renamed with the .jar extension and will have a valid signature according Microsoft Windows,” Quintero wrote.

But according to Quintero, while Microsoft’s security team validated his findings, the company chose not to address the problem at the time.

“Microsoft has decided that it will not be fixing this issue in the current versions of Windows and agreed we are able to blog about this case and our findings publicly,” his blog post concluded.

Tal Be’ery, founder of Zengo, and Peleg Hadar, senior security researcher at SafeBreach Labs, penned a blog post on Sunday that pointed to a file uploaded to VirusTotal in August 2018 that abused the spoofing weakness, which has been dubbed GlueBall. The last time that August 2018 file was scanned at VirusTotal (Aug 14, 2020), it was detected as a malicious Java trojan by 28 of 59 antivirus programs.

Continue reading →


11
Aug 20

Microsoft Patch Tuesday, August 2020 Edition

Microsoft today released updates to plug at least 120 security holes in its Windows operating systems and supported software, including two newly discovered vulnerabilities that are actively being exploited. Yes, good people of the Windows world, it’s time once again to backup and patch up!

At least 17 of the bugs squashed in August’s patch batch address vulnerabilities Microsoft rates as “critical,” meaning they can be exploited by miscreants or malware to gain complete, remote control over an affected system with little or no help from users. This is the sixth month in a row Microsoft has shipped fixes for more than 100 flaws in its products.

The most concerning of these appears to be CVE-2020-1380, which is a weaknesses in Internet Explorer that could result in system compromise just by browsing with IE to a hacked or malicious website. Microsoft’s advisory says this flaw is currently being exploited in active attacks.

The other flaw enjoying active exploitation is CVE-2020-1464, which is a “spoofing” bug in virtually all supported versions of Windows that allows an attacker to bypass Windows security features and load improperly signed files. For more on this flaw, see Microsoft Put Off Fixing Zero for 2 Years.

Trend Micro’s Zero Day Initiative points to another fix — CVE-2020-1472 — which involves a critical issue in Windows Server versions that could let an unauthenticated attacker gain administrative access to a Windows domain controller and run an application of their choosing. A domain controller is a server that responds to security authentication requests in a Windows environment, and a compromised domain controller can give attackers the keys to the kingdom inside a corporate network.

“It’s rare to see a Critical-rated elevation of privilege bug, but this one deserves it,” said ZDI’S Dustin Childs. “What’s worse is that there is not a full fix available.”

Perhaps the most “elite” vulnerability addressed this month earned the distinction of being named CVE-2020-1337, and refers to a security hole in the Windows Print Spooler service that could allow an attacker or malware to escalate their privileges on a system if they were already logged on as a regular (non-administrator) user.

Satnam Narang at Tenable notes that CVE-2020-1337 is a patch bypass for CVE-2020-1048, another Windows Print Spooler vulnerability that was patched in May 2020. Narang said researchers found that the patch for CVE-2020-1048 was incomplete and presented their findings for CVE-2020-1337 at the Black Hat security conference earlier this month. More information on CVE-2020-1337, including a video demonstration of a proof-of-concept exploit, is available here. Continue reading →


14
Jul 20

‘Wormable’ Flaw Leads July Microsoft Patches

Microsoft today released updates to plug a whopping 123 security holes in Windows and related software, including fixes for a critical, “wormable” flaw in Windows Server versions that Microsoft says is likely to be exploited soon. While this particular weakness mainly affects enterprises, July’s care package from Redmond has a little something for everyone. So if you’re a Windows (ab)user, it’s time once again to back up and patch up (preferably in that order).

Top of the heap this month in terms of outright scariness is CVE-2020-1350, which concerns a remotely exploitable bug in more or less all versions of Windows Server that attackers could use to install malicious software simply by sending a specially crafted DNS request.

Microsoft said it is not aware of reports that anyone is exploiting the weakness (yet), but the flaw has been assigned a CVSS score of 10, which translates to “easy to attack” and “likely to be exploited.”

“We consider this to be a wormable vulnerability, meaning that it has the potential to spread via malware between vulnerable computers without user interaction,” Microsoft wrote in its documentation of CVE-2020-1350. “DNS is a foundational networking component and commonly installed on Domain Controllers, so a compromise could lead to significant service interruptions and the compromise of high level domain accounts.”

CVE-2020-1350 is just the latest worry for enterprise system administrators in charge of patching dangerous bugs in widely-used software. Over the past couple of weeks, fixes for flaws with high severity ratings have been released for a broad array of software products typically used by businesses, including Citrix, F5, Juniper, Oracle and SAP. This at a time when many organizations are already short-staffed and dealing with employees working remotely thanks to the COVID-19 pandemic.

The Windows Server vulnerability isn’t the only nasty one addressed this month that malware or malcontents can use to break into systems without any help from users. A full 17 other critical flaws fixed in this release tackle security weaknesses that Microsoft assigned its most dire “critical” rating, such as in Office, Internet Exploder, SharePoint, Visual Studio, and Microsoft’s .NET Framework. Continue reading →


9
Jun 20

Microsoft Patch Tuesday, June 2020 Edition

Microsoft today released software patches to plug at least 129 security holes in its Windows operating systems and supported software, by some accounts a record number of fixes in one go for the software giant. None of the bugs addressed this month are known to have been exploited or detailed prior to today, but there are a few vulnerabilities that deserve special attention — particularly for enterprises and employees working remotely.

June marks the fourth month in a row that Microsoft has issued fixes to address more than 100 security flaws in its products. Eleven of the updates address problems Microsoft deems “critical,” meaning they could be exploited by malware or malcontents to seize complete, remote control over vulnerable systems without any help from users.

A chief concern among the panoply of patches is a trio of vulnerabilities in the Windows file-sharing technology (a.k.a. Microsoft Server Message Block or “SMB” service). Perhaps most troubling of these (CVE-2020-1301) is a remote code execution bug in SMB capabilities built into Windows 7 and Windows Server 2008 systems — both operating systems that Microsoft stopped supporting with security updates in January 2020. One mitigating factor with this flaw is that an attacker would need to be already authenticated on the network to exploit it, according to security experts at Tenable.

The SMB fixes follow closely on news that proof-of-concept code was published this week that would allow anyone to exploit a critical SMB flaw Microsoft patched for Windows 10 systems in March (CVE-2020-0796). Unlike this month’s critical SMB bugs, CVE-2020-0796 does not require the attacker to be authenticated to the target’s network. And with countless company employees now working remotely, Windows 10 users who have not yet applied updates from March or later could be dangerously exposed right now. Continue reading →


12
May 20

Microsoft Patch Tuesday, May 2020 Edition

Microsoft today issued software updates to plug at least 111 security holes in Windows and Windows-based programs. None of the vulnerabilities were labeled as being publicly exploited or detailed prior to today, but as always if you’re running Windows on any of your machines it’s time once again to prepare to get your patches on.

May marks the third month in a row that Microsoft has pushed out fixes for more than 110 security flaws in its operating system and related software. At least 16 of the bugs are labeled “Critical,” meaning ne’er-do-wells can exploit them to install malware or seize remote control over vulnerable systems with little or no help from users.

But focusing solely on Microsoft’s severity ratings may obscure the seriousness of the flaws being addressed this month. Todd Schell, senior product manager at security vendor Ivanti, notes that if one looks at the “exploitability assessment” tied to each patch — i.e., how likely Microsoft considers each can and will be exploited for nefarious purposes — it makes sense to pay just as much attention to the vulnerabilities Microsoft has labeled with the lesser severity rating of “Important.”

Virtually all of the non-critical flaws in this month’s batch earned Microsoft’s “Important” rating.

“What is interesting and often overlooked is seven of the ten [fixes] at higher risk of exploit are only rated as Important,” Schell said. “It is not uncommon to look to the critical vulnerabilities as the most concerning, but many of the vulnerabilities that end up being exploited are rated as Important vs Critical.”

For example, Satnam Narang from Tenable notes that two remote code execution flaws in Microsoft Color Management (CVE-2020-1117) and Windows Media Foundation (CVE-2020-1126) could be exploited by tricking a user into opening a malicious email attachment or visiting a website that contains code designed to exploit the vulnerabilities. However, Microsoft rates these vulnerabilities as “Exploitation Less Likely,” according to their Exploitability Index.

In contrast, three elevation of privilege vulnerabilities that received a rating of “Exploitation More Likely” were also patched, Narang notes. These include a pair of “Important” flaws in Win32k (CVE-2020-1054, CVE-2020-1143) and one in the Windows Graphics Component (CVE-2020-1135). Elevation of Privilege vulnerabilities are used by attackers once they’ve managed to gain access to a system in order to execute code on their target systems with elevated privileges. There are at least 56 of these types of fixes in the May release.

Schell says if your organization’s plan for prioritizing the deployment of this month’s patches stops at vendor severity or even CVSS scores above a certain level you may want to reassess your metrics.

“Look to other risk metrics like Publicly Disclosed, Exploited (obviously), and Exploitability Assessment (Microsoft specific) to expand your prioritization process,” he advised.

Continue reading →