Posts Tagged: zero day


26
Feb 20

Zyxel 0day Affects its Firewall Products, Too

On Monday, networking hardware maker Zyxel released security updates to plug a critical security hole in its network attached storage (NAS) devices that is being actively exploited by crooks who specialize in deploying ransomware. Today, Zyxel acknowledged the same flaw is present in many of its firewall products.

This week’s story on the Zyxel patch was prompted by the discovery that exploit code for attacking the flaw was being sold in the cybercrime underground for $20,000. Alex Holden, the security expert who first spotted the code for sale, said at the time the vulnerability was so “stupid” and easy to exploit that he wouldn’t be surprised to find other Zyxel products were similarly affected.

Now it appears Holden’s hunch was dead-on.

“We’ve now completed the investigation of all Zyxel products and found that firewall products running specific firmware versions are also vulnerable,” Zyxel wrote in an email to KrebsOnSecurity. “Hotfixes have been released immediately, and the standard firmware patches will be released in March.”

The updated security advisory from Zyxel states the exploit works against its UTM, ATP, and VPN firewalls running firmware version ZLD V4.35 Patch 0 through ZLD V4.35 Patch 2, and that those with firmware versions before ZLD V4.35 Patch 0 are not affected.

Zyxel’s new advisory suggests that some affected firewall product won’t be getting hotfixes or patches for this flaw, noting that the affected products listed in the advisory are only those which are “within their warranty support period.”

Indeed, while the exploit also works against more than a dozen of Zyxel’s NAS product lines, the company only released updates for NAS products that were newer than 2016. Its advice for those still using those unsupported NAS devices? “Do not leave the product directly exposed to the internet. If possible, connect it to a security router or firewall for additional protection.”

Hopefully, your vulnerable, unsupported Zyxel NAS isn’t being protected by a vulnerable, unsupported Zyxel firewall product.

CERT’s advisory on the flaw rate this vulnerability at a “10” — its most severe. My advice? If you can’t patch it, pitch it. The zero-day sales thread first flagged by Holden also hinted at the presence of post-authentication exploits in many Zyxel products, but the company did not address those claims in its security advisories.

Recent activity suggests that attackers known for deploying ransomware have been actively working to test the zero-day for use against targets. Holden said the exploit is now being used by a group of bad guys who are seeking to fold the exploit into Emotet, a powerful malware tool typically disseminated via spam that is frequently used to seed a target with malcode which holds the victim’s files for ransom.

“To me, a 0day exploit in Zyxel is not as scary as who bought it,” he said. “The Emotet guys have been historically targeting PCs, laptops and servers, but their venture now into IoT devices is very disturbing.”


24
Feb 20

Zyxel Fixes 0day in Network Storage Devices

Patch comes amid active exploitation by ransomware gangs

Networking hardware vendor Zyxel today released an update to fix a critical flaw in many of its network attached storage (NAS) devices that can be used to remotely commandeer them. The patch comes 12 days after KrebsOnSecurity alerted the company that precise instructions for exploiting the vulnerability were being sold for $20,000 in the cybercrime underground.

Based in Taiwan, Zyxel Communications Corp. (a.k.a “ZyXEL”) is a maker of networking devices, including Wi-Fi routers, NAS products and hardware firewalls. The company has roughly 1,500 employees and boasts some 100 million devices deployed worldwide. While in many respects the class of vulnerability addressed in this story is depressingly common among Internet of Things (IoT) devices, the flaw is notable because it has attracted the interest of groups specializing in deploying ransomware at scale.

KrebsOnSecurity first learned about the flaw on Feb. 12 from Alex Holden, founder of Milwaukee-based security firm Hold Security. Holden had obtained a copy of the exploit code, which allows an attacker to remotely compromise more than a dozen types of Zyxel NAS products remotely without any help from users.

A snippet from the documentation provided by 500mhz for the Zyxel 0day.

Holden said the seller of the exploit code — a ne’er-do-well who goes by the nickname “500mhz” –is known for being reliable and thorough in his sales of 0day exploits (a.k.a. “zero-days,” these are vulnerabilities in hardware or software products that vendors first learn about when exploit code and/or active exploitation shows up online).

For example, this and previous zero-days for sale by 500mhz came with exhaustive documentation detailing virtually everything about the flaw, including any preconditions needed to exploit it, step-by-step configuration instructions, tips on how to remove traces of exploitation, and example search links that could be used to readily locate thousands of vulnerable devices.

500mhz’s profile on one cybercrime forum states that he is constantly buying, selling and trading various 0day vulnerabilities.

“In some cases, it is possible to exchange your 0day with my existing 0day, or sell mine,” his Russian-language profile reads.

The profile page of 500mhz, translated from Russian to English via Google Chrome.

PARTIAL PATCH

KrebsOnSecurity first contacted Zyxel on Feb. 12, sharing a copy of the exploit code and description of the vulnerability. When four days elapsed without any response from the vendor to notifications sent via multiple methods, this author shared the same information with vulnerability analysts at the U.S. Department of Homeland Security (DHS) and with the CERT Coordination Center (CERT/CC), a partnership between DHS and Carnegie Mellon University.

Less than 24 hours after contacting DHS and CERT/CC, KrebsOnSecurity heard back from Zyxel, which thanked KrebsOnSecurity for the alert without acknowledging its failure to respond until they were sent the same information by others.

“Thanks for flagging,” Zyxel’s team wrote on Feb. 17. “We’ve just received an alert of the same vulnerabilities from US-CERT over the weekend, and we’re now in the process of investigating. Still, we heartily appreciate you bringing it to our attention.”

Earlier today, Zyxel sent a message saying it had published a security advisory and patch for the zero-day exploit in some of its affected products. The vulnerable devices include NAS542, NAS540, NAS520, NAS326, NSA325 v2, NSA325, NSA320S, NSA320, NSA310S, NSA310, NSA221, NSA220+, NSA220, and NSA210. The flaw is designated as CVE-2020-9054.

However, many of these devices are no longer supported by Zyxel and will not be patched. Zyxel’s advice for those users is simply “do not leave the product directly exposed to the internet.”

“If possible, connect it to a security router or firewall for additional protection,” the advisory reads.

Holden said given the simplicity of the exploit — which allows an attacker to seize remote control over an affected device by injecting just two characters to the username field of the login panel for Zyxel NAS devices — it’s likely other Zyxel products may have related vulnerabilities.

“Considering how stupid this exploit is, I’m guessing this is not the only one of its class in their products,” he said.

CERT’s advisory on the flaw rates it at a “10” — its most severe. The advisory includes additional mitigation instructions, including a proof-of-concept exploit that has the ability to power down affected Zyxel devices.

Continue reading →


8
Mar 17

WikiLeaks Dumps Docs on CIA’s Hacking Tools

WikiLeaks on Tuesday dropped one of its most explosive word bombs ever: A secret trove of documents apparently stolen from the U.S. Central Intelligence Agency (CIA) detailing methods of hacking everything from smart phones and TVs to compromising Internet routers and computers. KrebsOnSecurity is still digesting much of this fascinating data cache, but here are some first impressions based on what I’ve seen so far.

First, to quickly recap what happened: In a post on its site, WikiLeaks said the release — dubbed “Vault 7” — was the largest-ever publication of confidential documents on the agency. WikiLeaks is promising a series of these document caches; this first one includes more than 8,700 files allegedly taken from a high-security network inside CIA’s Center for Cyber Intelligence in Langley, Va.

The home page for the CIA's "Weeping Angel" project, which sought to exploit flaws that could turn certain 2013-model Samsung "smart" TVs into remote listening posts.

The home page for the CIA’s “Weeping Angel” project, which sought to exploit flaws that could turn certain 2013-model Samsung “smart” TVs into remote listening posts.

“Recently, the CIA lost control of the majority of its hacking arsenal including malware, viruses, trojans, weaponized ‘zero day’ exploits, malware remote control systems and associated documentation,” WikiLeaks wrote. “This extraordinary collection, which amounts to more than several hundred million lines of code, gives its possessor the entire hacking capacity of the CIA. The archive appears to have been circulated among former U.S. government hackers and contractors in an unauthorized manner, one of whom has provided WikiLeaks with portions of the archive.”

Wikileaks said it was calling attention to the CIA’s global covert hacking program, its malware arsenal and dozens of weaponized exploits against “a wide range of U.S. and European company products, includ[ing] Apple’s iPhone, Google’s Android and Microsoft’s Windows and even Samsung TVs, which are turned into covert microphones.”

The documents for the most part don’t appear to include the computer code needed to exploit previously unknown flaws in these products, although WikiLeaks says those exploits may show up in a future dump. This collection is probably best thought of as an internal corporate wiki used by multiple CIA researchers who methodically found and documented weaknesses in a variety of popular commercial and consumer electronics.

For example, the data dump lists a number of exploit “modules” available to compromise various models of consumer routers made by companies like Linksys, Microtik and Zyxel, to name a few. CIA researchers also collated several pages worth of probing and testing weaknesses in business-class devices from Ciscowhose powerful routers carry a decent portion of the Internet’s traffic on any given day. Craig Dods, a researcher with Cisco’s rival Juniper, delves into greater detail on the Cisco bugs for anyone interested (Dods says he found no exploits for Juniper products in the cache, yet). Meanwhile, Cisco has published its own blog post on the matter.

WHILE MY SMART TV GENTLY WEEPS

Some of the exploits discussed in these leaked CIA documents appear to reference full-on, remote access vulnerabilities. However, a great many of the documents I’ve looked at seem to refer to attack concepts or half-finished exploits that may be limited by very specific requirements — such as physical access to the targeted device.

The “Weeping Angelproject’s page from 2014 is a prime example: It discusses ways to turn certain 2013-model Samsung “smart TVs” into remote listening devices; methods for disabling the LED lights that indicate the TV is on; and suggestions for fixing a problem with the exploit in which the WiFi interface on the TV is disabled when the exploit is run.

ToDo / Future Work:
Build a console cable

Turn on or leave WiFi turned on in Fake-Off mode

Parse unencrypted audio collection
Clean-up the file format of saved audio. Add encryption??

According to the documentation, Weeping Angel worked as long as the target hadn’t upgraded the firmware on the Samsung TVs. It also said the firmware upgrade eliminated the “current installation method,” which apparently required the insertion of a booby-trapped USB device into the TV.

Don’t get me wrong: This is a serious leak of fairly sensitive information. And I sincerely hope Wikileaks decides to work with researchers and vendors to coordinate the patching of flaws leveraged by the as-yet unreleased exploit code archive that apparently accompanies this documentation from the CIA.

But in reading the media coverage of this leak, one might be led to believe that even if you are among the small minority of Americans who have chosen to migrate more of their communications to privacy-enhancing technologies like Signal or WhatsApp, it’s all futility because the CIA can break it anyway.

Perhaps a future cache of documents from this CIA division will change things on this front, but an admittedly cursory examination of these documents indicates that the CIA’s methods for weakening the privacy of these tools all seem to require attackers to first succeed in deeply subverting the security of the mobile device — either through a remote-access vulnerability in the underlying operating system or via physical access to the target’s phone.

As Bloomberg’s tech op-ed writer Leonid Bershidsky notes, the documentation released here shows that these attacks are “not about mass surveillance — something that should bother the vast majority of internet users — but about monitoring specific targets.”

By way of example, Bershidsky points to a tweet yesterday from Open Whisper Systems (the makers of the Signal private messaging app) which observes that, “The CIA/Wikileaks story today is about getting malware onto phones, none of the exploits are in Signal or break Signal Protocol encryption.”

The company went on to say that because more online services are now using end-to-end encryption to prevent prying eyes from reading communications that are intercepted in-transit, intelligence agencies are being pushed “from undetectable mass surveillance to expensive, high-risk, targeted attacks.”

A tweet from Open Whisper Systems, the makers of the popular mobile privacy app Signal.

A tweet from Open Whisper Systems, the makers of the popular mobile privacy app Signal.

Continue reading →


9
Nov 16

Patch Tuesday, 2016 U.S. Election Edition

Let’s get this out of the way up front: Having “2016 election” in the headline above is probably the only reason anyone might read this story today. It remains unclear whether Republicans and Democrats can patch things up after a bruising and divisive election, but thanks to a special Election Day Patch Tuesday hundreds of millions of Adobe and Microsoft users have some more immediate patching to do.

As the eyes of the world stayed glued to screens following the U.S. presidential election through the night, Microsoft and Adobe were busy churning out a large number of new security updates for Windows, MS Office, Flash Player and other software. If you use Flash Player or Microsoft products, please take a deep breath and read on.

brokenwindows

Regularly scheduled on the second Tuesday of each month, this month’s “Patch Tuesday” fell squarely on Election Day in the United States and included 14 patch bundles. Those patches fixed a total of 68 unique security flaws in Windows and related software.

Six of the 14 patches carry Microsoft’s most’s-dire “critical” label, meaning they fix bugs that malware or miscreants could use to remotely compromise vulnerable PCs without any help from users apart from maybe visiting a hacked or malicious Web site.

Microsoft says two of the software flaws addressed this week are already being exploited in active attacks. It also warned that three of the software vulnerabilities were publicly detailed prior to the release of these fixes – potentially giving attackers a head start in figuring out how to exploit the bugs.

MS16-129 is our usual dogs breakfast of remote code execution vulnerabilities in the Microsoft Edge browser, impacting both HTML rendering and scripting,” said Bobby Kuzma, systems engineer at Core Security. “MS16-130 contains  a privilege escalation in the onscreen keyboard function from Vista forward. That’s great news for anyone running touchscreen kiosks that are supposedly locked down.” Continue reading →


11
Oct 16

Microsoft: No More Pick-and-Choose Patching

Adobe and Microsoft today each issued updates to fix critical security flaws in their products. Adobe’s got fixes for Acrobat and Flash Player ready. Microsoft’s patch bundle for October includes fixes for at least five separate “zero-day” vulnerabilities — dangerous flaws that attackers were already exploiting prior to today’s patch release. Also notable this month is that Microsoft is changing how it deploys security updates, removing the ability for Windows users to pick and choose which individual patches to install.

brokenwindowsZero-day vulnerabilities describe flaws that even the makers of the targeted software don’t know about before they start seeing the flaws exploited in the wild, meaning the vendor has “zero days” to fix the bugs.

According to security vendor Qualys, Patch Tuesday updates fix zero-day bugs in Internet Explorer and Edge — the default browsers on different versions of Windows. MS16-121 addresses a zero-day in Microsoft Office. Another zero-day flaw affects GDI+ — a graphics component built into Windows that can be exploitable through the browser. The final zero-day is present in the Internet Messaging component of Windows.

Starting this month, home and business Windows users will no longer be able to pick and choose which updates to install and which to leave for another time. For example, I’ve often advised home users to hold off on installing .NET updates until all other patches for the month are applied — reasoning that .NET updates are very large and in my experience have frequently been found to be the source of problems when applying huge numbers of patches simultaneously.

But that cafeteria-style patching goes out the…err…Windows with this month’s release. Microsoft made the announcement in May of this year and revisited the subject again in August to add more detail behind its decision:

“Historically, we have released individual patches for these platforms, which allowed you to be selective with the updates you deployed,” wrote Nathan Mercer, a senior product marketing manager at Microsoft. “This resulted in fragmentation where different PCs could have a different set of updates installed leading to multiple potential problems:

  • Various combinations caused sync and dependency errors and lower update quality
  • Testing complexity increased for enterprises
  • Scan times increased
  • Finding and applying the right patches became challenging
  • Customers encountered issues where a patch was already released, but because it was in limited distribution it was hard to find and apply proactively

By moving to a rollup model, we bring a more consistent and simplified servicing experience to Windows 7 SP1 and 8.1, so that all supported versions of Windows follow a similar update servicing model. The new rollup model gives you fewer updates to manage, greater predictability, and higher quality updates. The outcome increases Windows operating system reliability, by eliminating update fragmentation and providing more proactive patches for known issues. Getting and staying current will also be easier with only one rollup update required. Rollups enable you to bring your systems up to date with fewer updates, and will minimize administrative overhead to install a large number of updates.”

Microsoft’s patch policy changes are slightly different for home versus business customers. Consumers on Windows 7 Service Pack 1 and Windows 8.1 will henceforth receive what Redmond is calling a “Monthly Rollup,” which addresses both security issues and reliability issues in a single update. The “Security-only updates” option — intended for enterprises and not available via Windows Update —  will only include new security patches that are released for that month. 

What this means is that if any part of the patch bundle breaks, the only option is to remove the entire bundle (instead of the offending patch, as was previously possible). I have no doubt this simplifies things for Microsoft and likely saves them a ton of money, but my concern is this will leave end-users unable to apply critical patches simply due to a single patch breaking something. Continue reading →


17
Jun 16

Adobe Update Plugs Flash Player Zero-Day

Adobe on Thursday issued a critical update for its ubiquitous Flash Player software that fixes three dozen security holes in the widely-used browser plugin, including at least one vulnerability that is already being exploited for use in targeted attacks.

brokenflash-aThe latest update brings Flash to v. 22.0.0.192 for Windows and Mac users alike. If you have Flash installed, you should update, hobble or remove Flash as soon as possible.

The smartest option is probably to ditch the program once and for all and significantly increase the security of your system in the process. I’ve got more on that approach (as well as slightly less radical solutions ) in A Month Without Adobe Flash Player.

If you choose to update, please do it today. The most recent versions of Flash should be available from this Flash distribution page or the Flash home page. Windows users who browse the Web with anything other than Internet Explorer may need to apply this patch twice, once with IE and again using the alternative browser (Firefox, Opera, e.g.). Chrome and IE should auto-install the latest Flash version on browser restart (I had to manually check for updates in Chrome an restart the browser to get the latest Flash version). Continue reading →


13
Apr 16

‘Badlock’ Bug Tops Microsoft Patch Batch

Microsoft released fixes on Tuesday to plug critical security holes in Windows and other software. The company issued 13 patches to tackle dozens of vulnerabilities, including a much-hyped “Badlock” file-sharing bug that appears ripe for exploitation. Also, Adobe updated its Flash Player release to address at least two-dozen flaws — in addition to the zero-day vulnerability Adobe patched last week.

Source: badlock.org

Source: badlock.org

The Windows patch that seems to be getting the most attention this month remedies seven vulnerabilities in Samba, a service used to manage file and print services across networks and multiple operating systems. This may sound innocuous enough, but attackers who gain access to private or corporate network could use these flaws to intercept traffic, view or modify user passwords, or shut down critical services.

According to badlock.org, a Web site set up to disseminate information about the widespread nature of the threat that this vulnerability poses, we are likely to see active exploitation of the Samba vulnerabilities soon.

Two of the Microsoft patches address flaws that were disclosed prior to Patch Tuesday. One of them is included in a bundle of fixes for Internet Explorer. A critical update for the Microsoft Graphics Component targets four vulnerabilities, two of which have been detected already in exploits in the wild, according to Chris Goettl at security vendor Shavlik.

Just a reminder: If you use Windows and haven’t yet taken advantage of the Enhanced Mitigation Experience Toolkit, a.k.a. “EMET,” you should definitely consider it. I describe the basic features and benefits of running EMET in this blog post from 2014 (yes, it’s time to revisit EMET in a future post), but the gist of it is that EMET helps block or blunt exploits against known and unknown Windows vulnerabilities and flaws in third-party applications that run on top of Windows. The latest version, v. 5.5, is available hereContinue reading →


11
Jul 15

Adobe To Fix Another Hacking Team Zero-Day

For the second time in a week, Adobe Systems Inc. says it plans fix a zero-day vulnerability in its Flash Player software that came to light after hackers broke into and posted online hundreds of gigabytes of data from Hacking Team, a controversial Italian company that’s long been accused of helping repressive regimes spy on dissident groups.

brokenflash-aIn an advisory published late Friday evening, Adobe said it plans to issue another Flash patch the week of July 13, 2015. “This vulnerability was reported to us following further investigation of the data published after the Hacking Team data breach,” the advisory notes.

Adobe said the flaw is present in the latest version of Flash for Windows, Mac and Linux systems, and that code showing attackers how to exploit this flaw is already available online.

There is every reason to believe this exploit will soon be folded into exploit kits, crimeware used to foist drive-by downloads when unsuspecting visitors browse to a hacked or booby-trapped site. On Wednesday, Adobe patched a different vulnerability in Flash that was exposed in the Hacking Team breach, but not before code designed to attack the flaw was folded into the Angler and Nuclear exploit kits.

If you were on the fence about removing or disabling Flash altogether, now would be a great time to reconsider. I recently blogged about my experience doing just that, and found I didn’t miss the program much at all after a month without it.


23
Jun 15

Emergency Patch for Adobe Flash Zero-Day

Adobe Systems Inc. today released an emergency update to fix a dangerous security hole in its widely-installed Flash Player browser plugin. The company warned that the vulnerability is already being exploited in targeted attacks, and urged users to update the program as quickly as possible.

In an advisory issued Tuesday morning, Adobe said the latest version of Flash — v. 18.0.0.194 on Windows and Mac OS X — fixes a critical flaw (CVE-2015-3113) that is being actively exploited in “limited, targeted attacks.” The company said systems running Internet Explorer for Windows 7 and below, as well as Firefox on Windows XP, are known targets of these exploits. Continue reading →


23
Jun 15

A Month Without Adobe Flash Player

I’ve spent the better part of the last month running a little experiment to see how much I would miss Adobe‘s buggy and insecure Flash Player software if I removed it from my systems altogether. Turns out, not so much.

brokenflash-aBrowser plugins are favorite targets for malware and miscreants because they are generally full of unpatched or undocumented security holes that cybercrooks can use to seize complete control over vulnerable systems. The Flash Player plugin is a stellar example of this: It is among the most widely used browser plugins, and it requires monthly patching (if not more frequently).

It’s also not uncommon for Adobe to release emergency fixes for the software to patch flaws that bad guys started exploiting before Adobe even knew about the bugs. This happened most recently in February 2015, and twice the month prior. Adobe also shipped out-of-band Flash fixes in December and November 2014.

Update, 11:30 a.m. ET: Oddly enough, Adobe just minutes ago released an out-of-band patch to fix a zero-day flaw in Flash.

Original story:

Time was, Oracle’s Java plugin was the favorite target of exploit kits, software tools made to be stitched into hacked or malicious sites and foist on visiting browsers a kitchen sink of exploits for various plugin vulnerabilities. Lately, however, it seems to pendulum has swung back in favor of exploits for Flash Player. A popular exploit kit known as Angler, for example, bundled a new exploit for a Flash vulnerability just three days after Adobe fixed it in April 2015.

So, rather than continue the patch madness and keep this insecure software installed, I decided to the pull the…er…plugin. I tend to (ab)use different browsers for different tasks, and so uninstalling the plugin was almost as simple as uninstalling Flash, except with Chrome, which bundles its own version of Flash Player. Fear not: disabling Flash in Chrome is simple enough. On a Windows, Mac, Linux or Chrome OS installation of Chrome, type “chrome:plugins” into the address bar, and on the Plug-ins page look for the “Flash” listing: To disable Flash, click the disable link (to re-enable it, click “enable”).

In almost 30 days, I only ran into just two instances where I encountered a site hosting a video that I absolutely needed to watch and that required Flash (an instructional video for a home gym that I could find nowhere else, and a live-streamed legislative hearing). For these, I opted to cheat and load the content into a Flash-enabled browser inside of a Linux virtual machine I have running inside of VirtualBox. In hindsight, it probably would have been easier simply to temporarily re-enable Flash in Chrome, and then disable it again until the need arose. Continue reading →