Category Archives: Time to Patch

Patch Tuesday, August 2019 Edition

Most Microsoft Windows (ab)users probably welcome the monthly ritual of applying security updates about as much as they look forward to going to the dentist: It always seems like you were there just yesterday, and you never quite know how it’s all going to turn out. Fortunately, this month’s patch batch from Redmond is mercifully light, at least compared to last month.

Okay, maybe a trip to the dentist’s office is still preferable. In any case, today is the second Tuesday of the month, which means it’s once again Patch Tuesday (or — depending on your setup and when you’re reading this post — Reboot Wednesday). Microsoft today released patches to fix some 93 vulnerabilities in Windows and related software, 35 of which affect various Server versions of Windows, and another 70 that apply to the Windows 10 operating system.

Although there don’t appear to be any zero-day vulnerabilities fixed this month — i.e. those that get exploited by cybercriminals before an official patch is available — there are several issues that merit attention.

Chief among those are patches to address four moderately terrifying flaws in Microsoft’s Remote Desktop Service, a feature which allows users to remotely access and administer a Windows computer as if they were actually seated in front of the remote computer. Security vendor Qualys says two of these weaknesses can be exploited remotely without any authentication or user interaction.

“According to Microsoft, at least two of these vulnerabilities (CVE-2019-1181 and CVE-2019-1182) can be considered ‘wormable’ and [can be equated] to BlueKeep,” referring to a dangerous bug patched earlier this year that Microsoft warned could be used to spread another WannaCry-like ransomware outbreak. “It is highly likely that at least one of these vulnerabilities will be quickly weaponized, and patching should be prioritized for all Windows systems.”

Fortunately, Remote Desktop is disabled by default in Windows 10, and as such these flaws are more likely to be a threat for enterprises that have enabled the application for various purposes. For those keeping score, this is the fourth time in 2019 Microsoft has had to fix critical security issues with its Remote Desktop service.

For all you Microsoft Edge and Internet Exploiter Explorer users, Microsoft has issued the usual panoply of updates for flaws that could be exploited to install malware after a user merely visits a hacked or booby-trapped Web site. Other equally serious flaws patched in Windows this month could be used to compromise the operating system just by convincing the user to open a malicious file (regardless of which browser the user is running).

As crazy as it may seem, this is the second month in a row that Adobe hasn’t issued a security update for its Flash Player browser plugin, which is bundled in IE/Edge and Chrome (although now hobbled by default in Chrome). However, Adobe did release important updates for its Acrobat and free PDF reader products.

If the tone of this post sounds a wee bit cantankerous, it might be because at least one of the updates I installed last month totally hosed my Windows 10 machine. I consider myself an equal OS abuser, and maintain multiple computers powered by a variety of operating systems, including Windows, Linux and MacOS.

Nevertheless, it is frustrating when being diligent about applying patches introduces so many unfixable problems that you’re forced to completely reinstall the OS and all of the programs that ride on top of it. On the bright side, my newly-refreshed Windows computer is a bit more responsive than it was before crash hell.

So, three words of advice. First off, don’t let Microsoft decide when to apply patches and reboot your computer. On the one hand, it’s nice Microsoft gives us a predictable schedule when it’s going to release patches. On the other, Windows 10 will by default download and install patches whenever it pleases, and then reboot the computer.

Unless you change that setting. Here’s a tutorial on how to do that. For all other Windows OS users, if you’d rather be alerted to new updates when they’re available so you can choose when to install them, there’s a setting for that in Windows Update.

Secondly, it doesn’t hurt to wait a few days to apply updates.  Very often fixes released on Patch Tuesday have glitches that cause problems for an indeterminate number of Windows systems. When this happens, Microsoft then patches their patches to minimize the same problems for users who haven’t yet applied the updates, but it sometimes takes a few days for Redmond to iron out the kinks.

Finally, please have some kind of system for backing up your files before applying any updates. You can use third-party software for this, or just the options built into Windows 10. At some level, it doesn’t matter. Just make sure you’re backing up your files, preferably following the 3-2-1 backup rule. Thankfully, I’m vigilant about backing up my files.

And, as ever, if you experience any problems installing any of these patches this month, please feel free to leave a comment about it below; there’s a good chance other readers have experienced the same and may even chime in here with some helpful tips.

Patch Tuesday Lowdown, July 2019 Edition

Microsoft today released software updates to plug almost 80 security holes in its Windows operating systems and related software. Among them are fixes for two zero-day flaws that are actively being exploited in the wild, and patches to quash four other bugs that were publicly detailed prior to today, potentially giving attackers a head start in working out how to use them for nefarious purposes.

Zero-days and publicly disclosed flaws aside for the moment, probably the single most severe vulnerability addressed in this month’s patch batch (at least for enterprises) once again resides in the component of Windows responsible for automatically assigning Internet addresses to host computers — a function called the “Windows DHCP server.”

The DHCP weakness (CVE-2019-0785) exists in most supported versions of Windows server, from Windows Server 2012 through Server 2019.

Microsoft said an unauthenticated attacker could use the DHCP flaw to seize total, remote control over vulnerable systems simply by sending a specially crafted data packet to a Windows computer. For those keeping count, this is the fifth time this year that Redmond has addressed such a critical flaw in the Windows DHCP client.

All told, only 15 of the 77 flaws fixed today earned Microsoft’s most dire “critical” rating, a label assigned to flaws that malware or miscreants could exploit to commandeer computers with little or no help from users. It should be noted that 11 of the 15 critical flaws are present in or are a key component of the browsers built into Windows — namely, Edge and Internet Exploder Explorer.

One of the zero-day flaws — CVE-2019-1132 — affects Windows 7 and Server 2008 systems. The other — CVE-2019-0880 — is present in Windows 8.1, Server 2012 and later operating systems. Both would allow an attacker to take complete control over an affected system, although each is what’s known as an “elevation of privilege” vulnerability, meaning an attacker would already need to have some level of access to the targeted system.

CVE-2019-0865 is a denial-of-service bug in a Microsoft open-source cryptographic library that could be used to tie up system resources on an affected Windows 8 computer. It was publicly disclosed a month ago by Google’s Project Zero bug-hunting operation after Microsoft reportedly failed to address it within Project Zero’s stated 90-day disclosure deadline.

The other flaw publicly detailed prior to today is CVE-2019-0887, which is a remote code execution flaw in the Remote Desktop Services (RDP) component of Windows. However, this bug also would require an attacker to already have compromised a target system.

Mercifully, there do not appear to be any security updates for Adobe Flash Player this month.

Standard disclaimer: Patching is important, but it usually doesn’t hurt to wait a few days before Microsoft irons out any wrinkles in the fixes, which sometimes introduce stability or usability issues with Windows after updating (KrebsOnSecurity will endeavor to update this post in the event that any big issues with these patches emerge).

As such, it’s a good idea to get in the habit of backing up your system — or at the very least your data — before applying any updates. The thing is, newer versions of Windows (e.g. Windows 10+) by default will go ahead and decide for you when that should be done (often this is in the middle of the night). But that setting can be changed.

If you experience any problems installing any of the patches this month, please feel free to leave a comment about it below; there’s a better-than-even chance that other readers have experienced the same and may even chime in with some helpful advice and tips.

Further reading:

Qualys Patch Tuesday Blog

Rapid7

Tenable [full disclosure: Tenable is an advertiser on this blog].

Microsoft Patch Tuesday, June 2019 Edition

Microsoft on Tuesday released updates to fix 88 security vulnerabilities in its Windows operating systems and related software. The most dangerous of these include four flaws for which there is already exploit code available. There’s also a scary bug affecting all versions of Microsoft Office that can be triggered by a malicious link or attachment. And of course Adobe has its customary monthly security update for Flash Player.

Microsoft says it has so far seen no exploitation against any of the four flaws that were disclosed publicly prior to their patching this week — nor against any of the 88 bugs quashed in this month’s release. All four are privilege escalation flaws: CVE-2019-1064 and CVE-2019-1069 affect Windows 10 and later; CVE-2019-1053 and CVE-2019-0973 both affect all currently supported versions of Windows.

Most of the critical vulnerabilities — those that can be exploited by malware or miscreants to infect systems without any action on the part of the user — are present in Microsoft’s browsers Internet Explorer and Edge.

According to Allan Liska, senior solutions architect at Recorded Future, serious vulnerabilities in this month’s patch batch reside in Microsoft Word (CVE-2019-1034 and CVE-2019-1035).

“This is another memory corruption vulnerability that requires an attacker to send a specially crafted Microsoft Word document for a victim to open, alternatively an attacker could convince a victim to click on a link to a website hosting a malicious Microsoft Word document,” Liska wrote. “This vulnerability affects all versions of Microsoft Word on Windows and Mac as well as Office 365. Given that Microsoft Word Documents are a favorite exploitation tool of cybercriminals, if this vulnerability is reverse engineered it could be widely exploited.”

Microsoft also pushed an update to plug a single critical security hole in Adobe’s Flash Player software, which is waning in use but it still is a target for malware purveyors. Google Chrome auto-updates Flash but also is now making users explicitly enable Flash every time they want to use it. By the summer of 2019 Google will make Chrome users go into their settings to enable it every time they want to run it.

Firefox also forces users with the Flash add-on installed to click in order to play Flash content; instructions for disabling or removing Flash from Firefox are here. Adobe will stop supporting Flash at the end of 2020.

Note that Windows 10 likes to install patches all in one go and reboot your computer on its own schedule. Microsoft doesn’t make it easy for Windows 10 users to change this setting, but it is possible. For all other Windows OS users, if you’d rather be alerted to new updates when they’re available so you can choose when to install them, there’s a setting for that in Windows Update. To get there, click the Windows key on your keyboard and type “windows update” into the box that pops up.

Staying up-to-date on Windows patches is good. Updating only after you’ve backed up your important data and files is even better. A good backup means you’re not pulling your hair out if the odd buggy patch causes problems booting the system. So do yourself a favor and backup your files before installing any patches.

As always, if you experience any problems installing any of the patches this month, please feel free to leave a comment about it below; there’s a good chance other readers have experienced the same and may even chime in here with some helpful tips.

Additional reading:

Martin Brinkmann’s take at Ghacks.net

Qualys on Patch Tuesday

SANS’s quick reference by severity