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Hackers Were Inside Citrix for Five Months

February 19, 2020 Leave a comment

Networking software giant Citrix Systems says malicious hackers were inside its networks for five months between 2018 and 2019, making off with personal and financial data on company employees, contractors, interns, job candidates and their dependents. The disclosure comes almost a year after Citrix acknowledged that digital intruders had broken in by probing its employee accounts for weak passwords.

Citrix provides software used by hundreds of thousands of clients worldwide, including most of the Fortune 100 companies. It is perhaps best known for selling virtual private networking (VPN) software that lets users remotely access networks and computers over an encrypted connection.

In March 2019, the Federal Bureau of Investigation (FBI) alerted Citrix they had reason to believe cybercriminals had gained access to the company’s internal network. The FBI told Citrix the hackers likely got in using a technique called “password spraying,” a relatively crude but remarkably effective attack that attempts to access a large number of employee accounts (usernames/email addresses) using just a handful of common passwords.

In a statement released at the time, Citrix said it appeared hackers “may have accessed and downloaded business documents,” and that it was still working to identify what precisely was accessed or stolen.

But in a letter sent to affected individuals dated Feb. 10, 2020, Citrix disclosed additional details about the incident. According to the letter, the attackers “had intermittent access” to Citrix’s internal network between Oct. 13, 2018 and Mar. 8, 2019, and that there was no evidence that the cybercrooks still remain in the company’s systems.

Citrix said the information taken by the intruders may have included Social Security Numbers or other tax identification numbers, driver’s license numbers, passport numbers, financial account numbers, payment card numbers, and/or limited health claims information, such as health insurance participant identification number and/or claims information relating to date of service and provider name.

It is unclear how many people received this letter, but the communication suggests Citrix is contacting a broad range of individuals who work or worked for the company at some point, as well as those who applied for jobs or internships there and people who may have received health or other benefits from the company by virtue of having a family member employed by the company.

Citrix’s letter was prompted by laws in virtually all U.S. states that require companies to notify affected consumers of any incident that jeopardizes their personal and financial data. While the notification does not specify whether the attackers stole proprietary data about the company’s software and internal operations, the intruders certainly had ample opportunity to access at least some of that information as well.

Shortly after Citrix initially disclosed the intrusion in March 2019, a little-known security company Resecurity claimed it had evidence Iranian hackers were responsible, had been in Citrix’s network for years, and had offloaded terabytes of data.

Iranian hackers recently have been blamed for hacking VPN servers around the world in a bid to plant backdoors in large corporate networks. A report released this week (PDF) by security firm ClearSky details how Iran’s government-backed hacking units have been busy exploiting security holes in popular VPN products from Citrix and a number of other software firms.

ClearSky says the attackers have focused on attacking VPN tools because they provide a long-lasting foothold at the targeted organizations, and frequently open the door to breaching additional companies through supply-chain attacks. The company says such tactics have allowed the Iranian hackers to gain persistent access to the networks of companies across a broad range of sectors, including IT, security, telecommunications, oil and gas, aviation, and government.

Among the VPN flaws available to attackers is a recently-patched vulnerability (CVE-2019-19781) in Citrix VPN servers dubbed “Shitrix” by some in the security community. The derisive nickname may have been chosen because while Citrix initially warned customers about the vulnerability in mid-December 2019, it didn’t start releasing patches to plug the holes until late January 2020 — roughly two weeks after attackers started using publicly released exploit code to break into vulnerable organizations.

How would your organization hold up to a password spraying attack? As the Citrix hack shows, if you don’t know you should probably check, and then act on the results accordingly. It’s a fair bet the bad guys are going to find out even if you don’t.

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Encoding Stolen Credit Card Data on Barcodes

February 18, 2020 Leave a comment

Crooks are constantly dreaming up new ways to use and conceal stolen credit card data. According to the U.S. Secret Service, the latest scheme involves stolen card information embedded in barcodes affixed to phony money network rewards cards. The scammers then pay for merchandise by instructing a cashier to scan the barcode and enter the expiration date and card security code.

This phony reloadable rewards card conceals stolen credit card data written to a barcode. The barcode and other card data printed on the card have been obfuscated. Image: U.S. Secret Service.

Earlier this month, the Secret Service documented a recent fraud incident in Texas involving a counterfeit club membership card containing a barcode, and a card expiration date and CVV printed below the barcode.

“Located underneath the barcode are instructions to the cashier on the steps necessary to complete the transaction,” reads an alert the Secret Service sent to law enforcement agencies. “They instruct the cashier to select card payment, scan the barcode, then enter the expiration date and CVV. In this instance, the barcode was encoded with a VISA credit card number.”

The instructions on the phony rewards card are designed to make the cashier think it’s a payment alternative designed for use exclusively at Sam’s Club and WalMart stores. When the transaction goes through, it’s recorded as card-not-present purchase.

“This appears to be an evolution of the traditional card-not-present fraud, and early indications are linking this type of activity to criminal organizations of Asian descent,” the Secret Service memo observed.

“As a result of this emerging trend, instead of finding a large number of re-encoded credit cards during a search, a subject may only possess stickers or cards with barcodes that contain stolen card data,” the alert continues. “Additionally, the barcodes could be stored on the subject’s cell phone. If barcodes are discovered in the field, it could be beneficial to utilize a barcode scanning app to check the barcode for credit card data.”

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Pay Up, Or We’ll Make Google Ban Your Ads

February 17, 2020 Leave a comment

A new email-based extortion scheme apparently is making the rounds, targeting Web site owners serving banner ads through Google’s AdSense program. In this scam, the fraudsters demand bitcoin in exchange for a promise not to flood the publisher’s ads with so much bot and junk traffic that Google’s automated anti-fraud systems suspend the user’s AdSense account for suspicious traffic.

A redacted extortion email targeting users of Google’s AdSense program.

Earlier this month, KrebsOnSecurity heard from a reader who maintains several sites that receive a fair amount of traffic. The message this reader shared began by quoting from an automated email Google’s systems might send if they detect your site is seeking to benefit from automated clicks. The message continues:

“Very soon the warning notice from above will appear at the dashboard of your AdSense account undoubtedly! This will happen due to the fact that we’re about to flood your site with huge amount of direct bot generated web traffic with 100% bounce ratio and thousands of IP’s in rotation — a nightmare for every AdSense publisher. More also we’ll adjust our sophisticated bots to open, in endless cycle with different time duration, every AdSense banner which runs on your site.”

The message goes on to warn that while the targeted site’s ad revenue will be briefly increased, “AdSense traffic assessment algorithms will detect very fast such a web traffic pattern as fraudulent.”

“Next an ad serving limit will be placed on your publisher account and all the revenue will be refunded to advertisers. This means that the main source of profit for your site will be temporarily suspended. It will take some time, usually a month, for the AdSense to lift your ad ban, but if this happens we will have all the resources needed to flood your site again with bad quality web traffic which will lead to second AdSense ban that could be permanent!”

The message demands $5,000 worth of bitcoin to forestall the attack. In this scam, the extortionists are likely betting that some publishers may see paying up as a cheaper alternative to having their main source of advertising revenue evaporate.

The reader who shared this email said while he considered the message likely to be a baseless threat, a review of his recent AdSense traffic statistics showed that detections in his “AdSense invalid traffic report” from the past month had increased substantially.

The reader, who asked not to be identified in this story, also pointed to articles about a recent AdSense crackdown in which Google announced it was enhancing its defenses by improving the systems that identify potentially invalid traffic or high risk activities before ads are served.

Google defines invalid traffic as “clicks or impressions generated by publishers clicking their own live ads,” as well as “automated clicking tools or traffic sources.”

“Pretty concerning, thought it seems this group is only saying they’re planning their attack,” the reader wrote.

Google declined to discuss this reader’s account, saying its contracts prevent the company from commenting publicly on a specific partner’s status or enforcement actions. But in a statement shared with KrebsOnSecurity, the company said the message appears to be a classic threat of sabotage, wherein an actor attempts to trigger an enforcement action against a publisher by sending invalid traffic to their inventory.

“We hear a lot about the potential for sabotage, it’s extremely rare in practice, and we have built some safeguards in place to prevent sabotage from succeeding,” the statement explained. “For example, we have detection mechanisms in place to proactively detect potential sabotage and take it into account in our enforcement systems.”

Google said it has extensive tools and processes to protect against invalid traffic across its products, and that most invalid traffic is filtered from its systems before advertisers and publishers are ever impacted.

“We have a help center on our website with tips for AdSense publishers on sabotage,” the statement continues. “There’s also a form we provide for publishers to contact us if they believe they are the victims of sabotage. We encourage publishers to disengage from any communication or further action with parties that signal that they will drive invalid traffic to their web properties. If there are concerns about invalid traffic, they should communicate that to us, and our Ad Traffic Quality team will monitor and evaluate their accounts as needed.”

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A Light at the End of Liberty Reserve’s Demise?

February 14, 2020 Leave a comment

In May 2013, the U.S. Justice Department seized Liberty Reserve, alleging the virtual currency service acted as a $6 billion financial hub for the cybercrime world. Prompted by assurances that the government would one day afford Liberty Reserve users a chance to reclaim any funds seized as part of the takedown, KrebsOnSecurity filed a claim shortly thereafter to see if and when this process might take place. This week, an investigator with the U.S. Internal Revenue service finally got in touch to discuss my claim.

Federal officials charged that Liberty Reserve facilitated a “broad range of criminal activity, including credit card fraud, identity theft, investment fraud, computer hacking, child pornography, and narcotics trafficking.” The government says from 2006 until the service’s takedown, Liberty Reserve processed an estimated 55 million financial transactions worth more than $6 billion, with more than 600,000 accounts associated with users in the United States alone.

While it’s clear that the digital currency system for years was the go-to money-moving vehicle for many engaged in dodgy online activities, it also was favored by users primarily because it offered a relatively anonymous way to send irrevocable transfers globally with low fees.

Indeed, the two stories I wrote about the closure of Liberty Reserve in 2013 remain among the most-read on this site, and have generated an enormous volume of emails from readers who saw many thousands of dollars held in legal limbo — much of it related to investments in online gaming platforms, payments to and from adult entertainment services, and various investment schemes.

The IRS official who contacted me was not authorized to be quoted in the media (and indeed did not initially realize he was speaking to a member of the press when he called). But he told me the government had recently obtained legal access to some of the funds held in overseas bank accounts that were used by Liberty Reserve, and that IRS investigators were now starting to contact people and vet any claims made in the wake of the takedown.

“We’re just getting to the point where we have received funds,” the investigator said. “We’ve started to contact people who originally contacted us, to vet their claims, make sure they weren’t involved in any illegal activity, and that the claim amounts match the records that we have.”

The official said he didn’t know how much money in total the government was seeking to return to former Liberty Reserve users. Requests for this information from the Justice Department office that prosecuted the case — the U.S. Attorney for the Southern District of New York — went unanswered.

The founder of Liberty Reserve, 45-year-old Arthur Budovsky, pleaded guilty in 2016 to conspiring to commit money laundering. He was sentenced to 20 years in prison, ordered to pay a $500,000 fine and forfeit $122 million in company funds.

If you filed a monetary claim in response to the Liberty Reserve seizure years back, you may have already been contacted by federal investigators, or you may be soon. But please know that fraudsters will likely seize on public awareness about the possible repatriation of funds to fleece the unwary: KrebsOnSecurity has received more than a few emails from readers over the years who fell for various phishing scams that promised to return funds lost at Liberty Reserve in exchange for a bogus “processing fee.”

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Microsoft Patch Tuesday, February 2020 Edition

February 11, 2020 Leave a comment

Microsoft today released updates to plug nearly 100 security holes in various versions of its Windows operating system and related software, including a zero-day vulnerability in Internet Explorer (IE) that is actively being exploited. Also, Adobe has issued a bevy of security updates for its various products, including Flash Player and Adobe Reader/Acrobat.

A dozen of the vulnerabilities Microsoft patched today are rated “critical,” meaning malware or miscreants could exploit them remotely to gain complete control over an affected system with little to no help from the user.

Last month, Microsoft released an advisory warning that attackers were exploiting a previously unknown flaw in IE. That vulnerability, assigned as CVE-2020-0674, has been patched with this month’s release. It could be used to install malware just by getting a user to browse to a malicious or hacked Web site.

Microsoft once again fixed a critical flaw in the way Windows handles shortcut (.lnk) files (CVE-2020-0729) that affects Windows 8 and 10 systems, as well as Windows Server 2008-2012. Allan Liska, intelligence analyst at Recorded Future, says Microsoft considers exploitation of the vulnerability unlikely, but that a similar vulnerability discovered last year, CVE-2019-1280, was being actively exploited by the Astaroth trojan as recently as September.

Another flaw fixed this month in Microsoft Exchange 2010 through 2019 may merit special attention. The bug could allow attackers to exploit the Exchange Server and execute arbitrary code just by sending a specially crafted email. This vulnerability (CVE-2020-0688) is rated “important” rather than “critical,” but Liska says it seems potentially dangerous, as Microsoft identifies this as a vulnerability that is likely to be exploited.

In addition, Redmond addressed a critical issue (CVE-2020-0618) in the way Microsoft SQL Server versions 2012-2016 handle page requests.

After a several-month respite from patches for its Flash Player browser plug-in, Adobe has once again blessed us with a security update for this program (fixes one critical flaw). Thankfully, Chrome and Firefox both now disable Flash by default, and Chrome and IE/Edge auto-update the program when new security updates are available. Adobe is slated to retire Flash Player later this year.

Other Adobe products for which the company shipped updates today include Experience Manager, Digital Editions, Framemaker and Acrobat/Reader (17 flaws). Security experts at Qualys note that on January 28th, Adobe also issued an out-of-band patch for Magento, labeled as Priority 2.

“While none of the vulnerabilities disclosed in Adobe’s release are known to be Actively Attacked today, all patches should be prioritized on systems with these products installed,” said Qualys’s Jimmy Graham.

Windows 7 users should be aware by now that while a fair number of flaws addressed this month by Microsoft affect Windows 7 systems, this operating system is no longer being supported with security updates (unless you’re an enterprise taking advantage of Microsoft’s paid extended security updates program, which is available to Windows 7 Professional and Windows 7 enterprise users).

If you rely on Windows 7 for day-to-day use, it’s probably time to think about upgrading to something newer. That might be a computer with Windows 10. Or maybe you have always wanted that shiny MacOS computer.

If cost is a primary motivator and the user you have in mind doesn’t do much with the system other than browsing the Web, perhaps a Chromebook or an older machine with a recent version of Linux is the answer (Ubuntu may be easiest for non-Linux natives). Whichever system you choose, it’s important to pick one that fits the owner’s needs and provides security updates on an ongoing basis.

Keep in mind that while staying up-to-date on Windows patches is a must, it’s important to make sure you’re updating only after you’ve backed up your important data and files. A reliable backup means you’re not losing your mind when the odd buggy patch causes problems booting the system.

So do yourself a favor and backup your files before installing any patches. Windows 10 even has some built-in tools to help you do that, either on a per-file/folder basis or by making a complete and bootable copy of your hard drive all at once.

As always, if you experience glitches or problems installing any of these patches this month, please consider leaving a comment about it below; there’s a better-than-even chance other readers have experienced the same and may chime in here with some helpful tips. Also, keep an eye on the AskWoody blog from Woody Leonhard, who keeps a close eye on buggy Microsoft updates each month.

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U.S. Charges 4 Chinese Military Officers in 2017 Equifax Hack

February 10, 2020 Leave a comment

The U.S. Justice Department today unsealed indictments against four Chinese officers of the People’s Liberation Army (PLA) accused of perpetrating the 2017 hack against consumer credit bureau Equifax that led to the theft of personal data on nearly 150 million Americans. DOJ officials said the four men were responsible for carrying out the largest theft of sensitive personal information by state-sponsored hackers ever recorded.

The nine-count indictment names Wu Zhiyong (吴志勇), Wang Qian (王乾), Xu Ke (许可) and Liu Lei (刘磊) as members of the PLA’s 54th Research Institute, a component of the Chinese military. They are each charged with three counts of conspiracy to commit computer fraud, economic espionage and wire fraud.

The government says the men disguised their hacking activity by routing attack traffic through 34 servers located in nearly 20 countries, using encrypted communications channels within Equifax’s network to blend in with normal network activity, and deleting log files daily to remove evidence of their meanderings through the company’s systems.

U.S. Attorney General Bill Barr said at a press conference today that the Justice Department doesn’t normally charge members of another country’s military with crimes (this is only the second time the agency has indicted Chinese military hackers). But in a carefully worded statement that seemed designed to deflect any criticism of past offensive cyber actions by the U.S. military against foreign targets, Barr said the DOJ did so in this case because the accused “indiscriminately” targeted American civilians on a massive scale.

“The United States, like other nations, has gathered intelligence throughout its history to ensure that national security and foreign policy decision makers have access to timely, accurate and insightful information,” Barr said. “But we collect information only for legitimate national security purposes. We don’t indiscriminately violate the privacy of ordinary citizens.”

FBI Deputy Director David Bowdich sought to address the criticism about the wisdom of indicting Chinese military officers for attacking U.S. commercial and government interests. Some security experts have charged that such indictments could both lessen the charges’ impact and leave American officials open to parallel criminal allegations from Chinese authorities.

“Some might wonder what good it does when these hackers are seemingly beyond our reach,” Bowdich said. “We answer this question all the time. We can’t take them into custody, try them in a court of law and lock them up. Not today, anyway. But one day these criminals will slip up, and when they do we’ll be there. We in law enforcement will not let hackers off the hook just because they’re halfway around the world.”

The attorney general said the attack on Equifax was just the latest in a long string of cyber espionage attacks that sought trade secrets and sensitive data from a broad range of industries, and including managed service providers and their clients worldwide, as well as U.S. companies in the nuclear power, metals and solar products industries.

“Indeed, about 80 percent of our economic espionage prosecutions have implicated the Chinese government, and about 60 percent of all trade secret thefts cases in recent years involved some connection with China,” he said.

The indictments come on the heels of a conference held by US government officials this week that detailed the breadth of hacking attacks involving the theft of intellectual property by Chinese entities.

“The FBI has about a thousand investigations involving China’s attempted theft of U.S.-based technology in all 56 of our field offices and spanning just about every industry and sector,” FBI Director Christopher Wray reportedly told attendees at the gathering in Washington, D.C., dubbed the “China Initiative Conference.”

At a time when increasingly combative trade relations with China combined with public fears over the ongoing Coronavirus flu outbreak are stirring Sinophobia in some pockets of the U.S. and other countries, Bowdich was quick to clarify that the government’s beef was with the Chinese government, not its citizenry.

“Our concern is not with the Chinese people or with the Chinese American,” he said. “It is with the Chinese government and the Chinese Communist Party. Confronting this threat directly doesn’t mean we should not do business with China, host Chinese students, welcome Chinese visitors or co-exist with China as a country on the world stage. What it does mean is when China violates our criminal laws and international norms, we will hold them accountable for it.”

A copy of the indictment is available here.

ANALYSIS

DOJ officials praised Equifax for their “close collaboration” in sharing data that helped investigators piece together this whodunnit. Attorney General Barr noted that the accused not only stole personal and in some cases financial data on Americans, they also stole Equifax’s trade secrets, which he said were “embodied by the compiled data and complex database designs used to store personal information.”

While the DOJ’s announcement today portrays Equifax in a somewhat sympathetic light, it’s important to remember that Equifax repeatedly has proven itself an extremely poor steward of the highly sensitive information that it holds on most Americans.

Equifax’s actions immediately before and after its breach disclosure on Sept 7, 2017 revealed a company so inept at managing its public response that one couldn’t help but wonder how it might have handled its internal affairs and security. Indeed, Equifax and its leadership careened from one feckless blunder to the next in a series of debacles that KrebsOnSecurity described at the time as a complete “dumpster fire” of a breach response.

For starters, the Web site that Equifax set up to let consumers check if they were affected by the breach consistently gave conflicting answers, and was initially flagged by some Web browsers as a potential phishing site.

Compounding the confusion, on Sept. 19, 2017, Equifax’s Twitter account told people looking for information about the breach to visit the wrong Web site, which also was blocked by multiple browsers as a phishing site.

And two weeks after its breach disclosure, Equifax began notifying consumers of their eligibility to enroll in free credit monitoring — but the messages did not come from Equifax’s domain and were in many other ways indistinguishable from a phishing attempt.

It soon emerged the intruders had gained access to Equifax’s systems by attacking a software vulnerability in an Internet-facing server that had been left unpatched for four months after security experts warned that the flaw was being broadly exploited. We also learned that the server in question was tied to an online dispute portal at Equifax, which the intruders quickly seeded with tools that allowed them to maintain access to the credit bureau’s systems.

This is especially notable because on Sept. 12, 2017 — just five days after Equifax went public with its breach — KrebsOnSecurity broke the news that the administrative account for a separate Equifax dispute resolution portal catering to consumers in Argentina was wide open, protected by perhaps the most easy-to-guess password combination ever: “admin/admin.”

A partial list of active and inactive Equifax employees in Argentina. This page also let anyone add or remove users at will, or modify existing user accounts.

Perhaps we all should have seen this megabreach coming. In May 2017, KrebsOnSecurity detailed how countless employees at many major U.S. companies suffered tax refund fraud with the IRS thanks to a laughably insecure portal at Equifax’s TALX payroll division, which provides online payroll, HR and tax services to thousands of U.S. firms.

Equifax’s TALX — now called Equifax Workforce Solutions — aided tax thieves by relying on outdated and insufficient consumer authentication methods.

In October 2017, KrebsOnSecurity showed how easy it was to learn the complete salary history of a large portion of Americans simply by knowing someone’s Social Security number and date of birth, thanks to yet another Equifax portal.

Around that same time, we also learned that at least two Equifax executives sought to profit from the disaster through insider trading just days prior to the breach announcement. Jun Ying, Equifax’s former chief information officer, dumped all of his stock in the company in late August 2017, realizing a gain of $480,000 and avoiding a loss of more than $117,000 when news of the breach dinged Equifax’s stock price.

Sudhakar Reddy Bonthu, a former manager at Equifax who was contracted to help the company with its breach response, bought 86 “put” options in Equifax stock on Sept. 1, 2017 that allowed him to profit when the company’s share price dropped. Bonthu was later sentenced to eight months of home confinement; Ying got four months in prison and one year of supervised release. Both were fined and/or ordered to pay back their ill-gotten gains.

While Equifax’s stock price took a steep hit in the months following its breach disclosure, shares in the company [NYSE:EFX] gained a whopping 50.5% in 2019, according to data from S&P Global Market Intelligence.

KrebsOnSecurity has long maintained that the 2017 breach at Equifax was not the work of financially-motivated identity thieves, as there has been exactly zero evidence to date that anything close to the size of the data cache stolen from that incident has shown up for sale in the cybercrime underground.

However, readers should understand that there are countless other companies with access to SSN, DOB and other information crooks need to apply for credit in your name that get hacked all the time, and that this data on a great many Americans is already for sale across various cybercrime bazaars.

Readers also should know that while identity theft protection services of the kind offered by Equifax and other companies may alert you if crooks open a new line of credit in your name, these services generally do nothing to stop that identity theft from taking place. ID theft protection services are most useful in helping people recover from such crimes.

As such, KrebsOnSecurity continues to encourage readers to place a freeze on their credit files with Equifax and the other major credit bureaus. This process puts you in control over who gets to grant credit in your name. Placing a freeze is now free for all Americans and their dependents. For more information on how to do that and what to expect from a freeze, please see this primer.

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Dangerous Domain Corp.com Goes Up for Sale

February 8, 2020 Leave a comment

As an early domain name investor, Mike O’Connor had by 1994 snatched up several choice online destinations, including bar.com, cafes.com, grill.com, place.com, pub.com and television.com. Some he sold over the years, but for the past 26 years O’Connor refused to auction perhaps the most sensitive domain in his stable — corp.com. It is sensitive because years of testing shows whoever wields it would have access to an unending stream of passwords, email and other proprietary data belonging to hundreds of thousands of systems at major companies around the globe.

Now, facing 70 and seeking to simplify his estate, O’Connor is finally selling corp.com. The asking price — $1.7 million — is hardly outlandish for a 4-letter domain with such strong commercial appeal. O’Connor said he hopes Microsoft Corp. will buy it, but fears they won’t and instead it will get snatched up by someone working with organized cybercriminals or state-funded hacking groups bent on undermining the interests of Western corporations.

One reason O’Connor hopes Microsoft will buy it is that by virtue of the unique way that Windows handles resolving domain names on a local network, virtually all of the computers trying to share sensitive data with corp.com are somewhat confused Windows PCs. More importantly, early versions of Windows actually encouraged the adoption of insecure settings that made it more likely Windows computers might try to share sensitive data with corp.com.

At issue is a problem known as “namespace collision,” a situation where domain names intended to be used exclusively on an internal company network end up overlapping with domains that can resolve normally on the open Internet.

Windows computers on an internal corporate network validate other things on that network using a Microsoft innovation called Active Directory, which is the umbrella term for a broad range of identity-related services in Windows environments. A core part of the way these things find each other involves a Windows feature called “DNS name devolution,” which is a kind of network shorthand that makes it easier to find other computers or servers without having to specify a full, legitimate domain name for those resources.

For instance, if a company runs an internal network with the name internalnetwork.example.com, and an employee on that network wishes to access a shared drive called “drive1,” there’s no need to type “drive1.internalnetwork.example.com” into Windows Explorer; typing “\\drive1\” alone will suffice, and Windows takes care of the rest.

But things can get far trickier with an internal Windows domain that does not map back to a second-level domain the organization actually owns and controls. And unfortunately, in early versions of Windows that supported Active Directory — Windows 2000 Server, for example — the default or example Active Directory path was given as “corp,” and many companies apparently adopted this setting without modifying it to include a domain they controlled.

Compounding things further, some companies then went on to build (and/or assimilate) vast networks of networks on top of this erroneous setting.

Now, none of this was much of a security concern back in the day when it was impractical for employees to lug their bulky desktop computers and monitors outside of the corporate network. But what happens when an employee working at a company with an Active Directory network path called “corp” takes a company laptop to the local Starbucks?

Chances are good that at least some resources on the employee’s laptop will still try to access that internal “corp” domain. And because of the way DNS name devolution works on Windows, that company laptop online via the Starbucks wireless connection is likely to then seek those same resources at “corp.com.”

In practical terms, this means that whoever controls corp.com can passively intercept private communications from hundreds of thousands of computers that end up being taken outside of a corporate environment which uses this “corp” designation for its Active Directory domain.

INSTANT CORPORATE BOTNET, ANYONE?

That’s according to Jeff Schmidt, a security expert who conducted a lengthy study on DNS namespace collisions funded in part by grants from the U.S. Department of Homeland Security. As part of that analysis, Schmidt convinced O’Connor to hold off selling corp.com so he and others could better understand and document the volume and types of traffic flowing to it each day.

During an eight month analysis of wayward internal corporate traffic destined for corp.com in 2019, Schmidt found more than 375,000 Windows PCs were trying to send this domain information it had no business receiving — including attempts to log in to internal corporate networks and access specific file shares on those networks.

For a brief period during that testing, Schmidt’s company JAS Global Advisors accepted connections at corp.com that mimicked the way local Windows networks handle logins and file-sharing attempts.

“It was terrifying,” Schmidt said. “We discontinued the experiment after 15 minutes and destroyed the data. A well-known offensive tester that consulted with JAS on this remarked that during the experiment it was ‘raining credentials’ and that he’d never seen anything like it.”

Likewise, JAS temporarily configured corp.com to accept incoming email.

“After about an hour we received in excess of 12 million emails and discontinued the experiment,” Schmidt said. “While the vast majority of the emails were of an automated nature, we found some of the emails to be sensitive and thus destroyed the entire corpus without further analysis.”

Schmidt said he and others concluded that whoever ends up controlling corp.com could have an instant botnet of well-connected enterprise machines.

“Hundreds of thousands of machines directly exploitable and countless more exploitable via lateral movement once in the enterprise,” he said. “Want an instant foothold into about 30 of the world’s largest companies according to the Forbes Global 2000? Control corp.com.”

THE EARLY ADVENTURES OF CORP.COM

Schmidt’s findings closely mirror what O’Connor discovered in the few years corp.com was live on the Internet after he initially registered it back in 1994. O’Connor said early versions of a now-defunct Web site building tool called Microsoft FrontPage suggested corporation.com (another domain registered early on by O’Connor) as an example domain in its setup wizard.

That experience, portions of which are still indexed by the indispensable Internet Archive, saw O’Connor briefly redirecting queries for the domain to the Web site of a local adult sex toy shop as a joke. He soon got angry emails from confused people who’d also CC’d Microsoft co-founder Bill Gates.

Archive.org’s index of corp.com from 1997, when its owner Mike O’Connor briefly enabled a Web site mainly to shame Microsoft for the default settings of its software.

O’Connor said he also briefly enabled an email server on corp.com, mainly out of morbid curiosity to see what would happen next.

“Right away I started getting sensitive emails, including pre-releases of corporate financial filings with The U.S. Securities and Exchange Commission, human resources reports and all kinds of scary things,” O’Connor recalled in an interview with KrebsOnSecurity. “For a while, I would try to correspond back to corporations that were making these mistakes, but most of them didn’t know what to do with that. So I finally just turned it off.”

TOXIC WASTE CLEANUP IS HARD

Microsoft declined to answer specific questions in response to Schmidt’s findings on the wayward corp.com traffic. But a spokesperson for the company shared a written statement acknowledging that “we sometimes reference ‘corp’ as a label in our naming documentation.”

“We recommend customers own second level domains to prevent being routed to the internet,” the statement reads, linking to this Microsoft Technet article on best practices for setting up domains in Active Directory.

Over the years, Microsoft has shipped several software updates to help decrease the likelihood of namespace collisions that could create a security problem for companies that still rely on Active Directory domains that do not map to a domain they control.

But both O’Connor and Schmidt say hardly any vulnerable organizations have deployed these fixes for two reasons. First, doing so requires the organization to take down its entire Active Directory network simultaneously for some period of time. Second, according to Microsoft applying the patch(es) will likely break or at least slow down a number of applications that the affected organization relies upon for day-to-day operations.

Faced with either or both of these scenarios, most affected companies probably decided the actual risk of not applying these updates was comparatively low, O’Connor said.

“The problem is that when you read the instructions for doing the repair, you realize that what they’re saying is, ‘Okay Megacorp, in order to apply this patch and for everything to work right, you have to take down all of your Active Directory services network-wide, and when you bring them back up after you applied the patch, a lot of your servers may not work properly’,” O’Connor said.

Curiously, Schmidt shared slides from a report submitted to a working group on namespace collisions suggesting that at least some of the queries corp.com received while he was monitoring it may have come from Microsoft’s own internal networks.

Image: JAS Global Advisors

“The reason I believe this is Microsoft’s issue to solve is that someone that followed Microsoft’s recommendations when establishing an active directory several years back now has a problem,” Schmidt said.

“Even if all patches are applied and updated to Windows 10,” he continued. “And the problem will persist while there are active directories named ‘corp’ – which is forever. More practically, if corp.com falls into bad hands, the impact will be on Microsoft enterprise clients – and at large scale – paying, Microsoft clients they should protect.”

Asked why he didn’t just give corp.com to Microsoft as an altruistic gesture, O’Connor said the software giant ought to be accountable for its products and mistakes.

“It seems to me that Microsoft should stand up and shoulder the burden of the mistake they made,” he said. “But they’ve shown no real interest in doing that, and so I’ve shown no interest in giving it to them. I don’t really need the money. I’m basically auctioning off a chemical waste dump because I don’t want to pass it on to my kids and burden them with it. My frustration here is the good guys don’t care and the bad guys probably don’t know about it. But I expect the bad guys would like it.”

Further reading:

Mitigating the Risk of DNS Namespace Collisions (PDF)

DEFCON 21 – DNS May Be Hazardous to your Health (Robert Stucke)

Mitigating the Risk of Name Collision-Based Man-in-the-Middle Attacks (PDF)

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