Patch Tuesday, October 2023 Edition

Microsoft today issued security updates for more than 100 newly-discovered vulnerabilities in its Windows operating system and related software, including four flaws that are already being exploited. In addition, Apple recently released emergency updates to quash a pair of zero-day bugs in iOS.

Apple last week shipped emergency updates in iOS 17.0.3 and iPadOS 17.0.3 in response to active attacks. The patch fixes CVE-2023-42724, which attackers have been using in targeted attacks to elevate their access on a local device.

Apple said it also patched CVE-2023-5217, which is not listed as a zero-day bug. However, as Bleeping Computer pointed out, this flaw is caused by a weakness in the open-source “libvpx” video codec library, which was previously patched as a zero-day flaw by Google in the Chrome browser and by Microsoft in Edge, Teams, and Skype products. For anyone keeping count, this is the 17th zero-day flaw that Apple has patched so far this year.

Fortunately, the zero-days affecting Microsoft customers this month are somewhat less severe than usual, with the exception of CVE-2023-44487. This weakness is not specific to Windows but instead exists within the HTTP/2 protocol used by the World Wide Web: Attackers have figured out how to use a feature of HTTP/2 to massively increase the size of distributed denial-of-service (DDoS) attacks, and these monster attacks reportedly have been going on for several weeks now.

Amazon, Cloudflare and Google all released advisories today about how they’re addressing CVE-2023-44487 in their cloud environments. Google’s Damian Menscher wrote on Twitter/X that the exploit — dubbed a “rapid reset attack” — works by sending a request and then immediately cancelling it (a feature of HTTP/2). “This lets attackers skip waiting for responses, resulting in a more efficient attack,” Menscher explained.

Natalie Silva, lead security engineer at Immersive Labs, said this flaw’s impact to enterprise customers could be significant, and lead to prolonged downtime.

“It is crucial for organizations to apply the latest patches and updates from their web server vendors to mitigate this vulnerability and protect against such attacks,” Silva said. In this month’s Patch Tuesday release by Microsoft, they have released both an update to this vulnerability, as well as a temporary workaround should you not be able to patch immediately.”

Microsoft also patched zero-day bugs in Skype for Business (CVE-2023-41763) and Wordpad (CVE-2023-36563). The latter vulnerability could expose NTLM hashes, which are used for authentication in Windows environments.

“It may or may not be a coincidence that Microsoft announced last month that WordPad is no longer being updated, and will be removed in a future version of Windows, although no specific timeline has yet been given,” said Adam Barnett, lead software engineer at Rapid7. “Unsurprisingly, Microsoft recommends Word as a replacement for WordPad.”

Other notable bugs addressed by Microsoft include CVE-2023-35349, a remote code execution weakness in the Message Queuing (MSMQ) service, a technology that allows applications across multiple servers or hosts to communicate with each other. This vulnerability has earned a CVSS severity score of 9.8 (10 is the worst possible). Happily, the MSMQ service is not enabled by default in Windows, although Immersive Labs notes that Microsoft Exchange Server can enable this service during installation.

Speaking of Exchange, Microsoft also patched CVE-2023-36778,  a vulnerability in all current versions of Exchange Server that could allow attackers to run code of their choosing. Rapid7’s Barnett said successful exploitation requires that the attacker be on the same network as the Exchange Server host, and use valid credentials for an Exchange user in a PowerShell session.

For a more detailed breakdown on the updates released today, see the SANS Internet Storm Center roundup. If today’s updates cause any stability or usability issues in Windows, AskWoody.com will likely have the lowdown on that.

Please consider backing up your data and/or imaging your system before applying any updates. And feel free to sound off in the comments if you experience any difficulties as a result of these patches.

3CX Breach Was a Double Supply Chain Compromise

We learned some remarkable new details this week about the recent supply-chain attack on VoIP software provider 3CX. The lengthy, complex intrusion has all the makings of a cyberpunk spy novel: North Korean hackers using legions of fake executive accounts on LinkedIn to lure people into opening malware disguised as a job offer; malware targeting Mac and Linux users working at defense and cryptocurrency firms; and software supply-chain attacks nested within earlier supply chain attacks.

In late March 2023, 3CX disclosed that its desktop applications for both Windows and macOS were compromised with malicious code that gave attackers the ability to download and run code on all machines where the app was installed. 3CX says it has more than 600,000 customers and 12 million users in a broad range of industries, including aerospace, healthcare and hospitality.

3CX hired incident response firm Mandiant, which released a report on Wednesday that said the compromise began in 2022 when a 3CX employee installed a malware-laced software package distributed via an earlier software supply chain compromise that began with a tampered installer for X_TRADER, a software package provided by Trading Technologies.

“This is the first time Mandiant has seen a software supply chain attack lead to another software supply chain attack,” reads the April 20 Mandiant report.

Mandiant found the earliest evidence of compromise uncovered within 3CX’s network was through the VPN using the employee’s corporate credentials, two days after the employee’s personal computer was compromised.

“Eventually, the threat actor was able to compromise both the Windows and macOS build environments,” 3CX said in an April 20 update on their blog.

Mandiant concluded that the 3CX attack was orchestrated by the North Korean state-sponsored hacking group known as Lazarus, a determination that was independently reached earlier by researchers at Kaspersky Lab and Elastic Security.

Mandiant found the compromised 3CX software would download malware that sought out new instructions by consulting encrypted icon files hosted on GitHub. The decrypted icon files revealed the location of the malware’s control server, which was then queried for a third stage of the malware compromise — a password stealing program dubbed ICONICSTEALER.

Meanwhile, the security firm ESET today published research showing remarkable similarities between the malware used in the 3CX supply chain attack and Linux-based malware that was recently deployed via fake job offers from phony executive profiles on LinkedIn. The researchers said this was the first time Lazarus had been spotted deploying malware aimed at Linux users.

As reported in a series last summer here, LinkedIn has been inundated this past year by fake executive profiles for people supposedly employed at a range of technology, defense, energy and financial companies. In many cases, the phony profiles spoofed chief information security officers at major corporations, and some attracted quite a few connections before their accounts were terminated.

Mandiant, Proofpoint and other experts say Lazarus has long used these bogus LinkedIn profiles to lure targets into opening a malware-laced document that is often disguised as a job offer. This ongoing North Korean espionage campaign using LinkedIn was first documented in August 2020 by ClearSky Security, which said the Lazarus group operates dozens of researchers and intelligence personnel to maintain the campaign globally.

Microsoft Corp., which owns LinkedIn, said in September 2022 that it had detected a wide range of social engineering campaigns using a proliferation of phony LinkedIn accounts. Microsoft said the accounts were used to impersonate recruiters at technology, defense and media companies, and to entice people into opening a malicious file. Microsoft found the attackers often disguised their malware as legitimate open-source software like Sumatra PDF and the SSH client Putty.

Microsoft attributed those attacks to North Korea’s Lazarus hacking group, although they’ve traditionally referred to this group as “ZINC“. That is, until earlier this month, when Redmond completely revamped the way it names threat groups; Microsoft now references ZINC as “Diamond Sleet.”

The ESET researchers said they found a new fake job lure tied to an ongoing Lazarus campaign on LinkedIn designed to compromise Linux operating systems. The malware was found inside of a document that offered an employment contract at the multinational bank HSBC.

“A few weeks ago, a native Linux payload was found on VirusTotal with an HSBC-themed PDF lure,” wrote ESET researchers Peter Kalnai and Marc-Etienne M.Leveille. “This completes Lazarus’s ability to target all major desktop operating systems. In this case, we were able to reconstruct the full chain, from the ZIP file that delivers a fake HSBC job offer as a decoy, up until the final payload.”

ESET said the malicious PDF file used in the scheme appeared to have a file extension of “.pdf,” but that this was a ruse. ESET discovered that the dot in the filename wasn’t a normal period but instead a Unicode character (U+2024) representing a “leader dot,” which is often used in tables of contents to connect section headings with the page numbers on which those sections begin.

“The use of the leader dot in the filename was probably an attempt to trick the file manager into treating the file as an executable instead of a PDF,” the researchers continued. “This could cause the file to run when double-clicked instead of opening it with a PDF viewer.”

ESET said anyone who opened the file would see a decoy PDF with a job offer from HSBC, but in the background the executable file would download additional malware payloads. The ESET team also found the malware was able to manipulate the program icon displayed by the malicious PDF, possibly because fiddling with the file extension could cause the user’s system to display a blank icon for the malware lure.

Kim Zetter, a veteran Wired.com reporter and now independent security journalist, interviewed Mandiant researchers who said they expect “many more victims” will be discovered among the customers of Trading Technologies and 3CX now that news of the compromised software programs is public.

“Mandiant informed Trading Technologies on April 11 that its X_Trader software had been compromised, but the software maker says it has not had time to investigate and verify Mandiant’s assertions,” Zetter wrote in her Zero Day newsletter on Substack. For now, it remains unclear whether the compromised X_Trader software was downloaded by people at other software firms.

If there’s a silver lining here, the X_Trader software had been decommissioned in April 2020 — two years before the hackers allegedly embedded malware in it.

“The company hadn’t released new versions of the software since that time and had stopped providing support for the product, making it a less-than-ideal vector for the North Korean hackers to infect customers,” Zetter wrote.

The Link Between AWM Proxy & the Glupteba Botnet

On December 7, 2021, Google announced it was suing two Russian men allegedly responsible for operating the Glupteba botnet, a global malware menace that has infected millions of computers over the past decade. That same day, AWM Proxy — a 14-year-old anonymity service that rents hacked PCs to cybercriminals — suddenly went offline. Security experts had long seen a link between Glupteba and AWM Proxy, but new research shows AWM Proxy’s founder is one of the men being sued by Google.

Launched in March 2008, AWM Proxy quickly became the largest service for crooks seeking to route their malicious Web traffic through compromised devices. In 2011, researchers at Kaspersky Lab showed that virtually all of the hacked systems for rent at AWM Proxy had been compromised by TDSS (a.k.a TDL-4 and Alureon), a stealthy “rootkit” that installs deep within infected PCs and loads even before the underlying Windows operating system boots up.

In March 2011, security researchers at ESET found TDSS was being used to deploy Glupteba, another rootkit that steals passwords and other access credentials, disables security software, and tries to compromise other devices on the victim’s network — such as Internet routers and media storage servers — for use in relaying spam or other malicious traffic.

Like its predecessor TDSS, Glupteba is primarily distributed through “pay-per-install” or PPI networks, and via traffic purchased from traffic distribution systems (TDS). Pay-per-install networks try to match cybercriminals who already have access to large numbers of hacked PCs with other crooks seeking broader distribution of their malware.

In a typical PPI network, clients will submit their malware—a spambot or password-stealing Trojan, for example —to the service, which in turn charges per thousand successful installations, with the price depending on the requested geographic location of the desired victims. One of the most common ways PPI affiliates generate revenue is by secretly bundling the PPI network’s installer with pirated software titles that are widely available for download via the web or from file-sharing networks.

Over the past decade, both Glupteba and AWM Proxy have grown substantially. When KrebsOnSecurity first covered AWM Proxy in 2011, the service was selling access to roughly 24,000 infected PCs scattered across dozens of countries. Ten years later, AWM Proxy was offering 10 times that number of hacked systems on any given day, and Glupteba had grown to more than one million infected devices worldwide.

There is also ample evidence to suggest that Glupteba may have spawned Meris, a massive botnet of hacked Internet of Things (IoT) devices that surfaced in September 2021 and was responsible for some of the largest and most disruptive distributed denial-of-service (DDoS) attacks the Internet has ever seen.

But on Dec. 7, 2021, Google announced it had taken technical measures to dismantle the Glupteba botnet, and filed a civil lawsuit (PDF) against two Russian men thought to be responsible for operating the vast crime machine. AWM Proxy’s online storefront disappeared that same day.

AWM Proxy quickly alerted its customers that the service had moved to a new domain, with all customer balances, passwords and purchase histories seamlessly ported over to the new home. However, subsequent takedowns targeting AWM Proxy’s domains and other infrastructure have conspired to keep the service on the ropes and frequently switching domains ever since.

Earlier this month, the United States, Germany, the Netherlands and the U.K. dismantled the “RSOCKS” botnet, a competing proxy service that had been in operation since 2014. KrebsOnSecurity has identified the owner of RSOCKS as a 35-year-old from Omsk, Russia who runs the world’s largest forum catering to spammers.

Shortly after last week’s story on the RSOCKS founder, I heard from Riley Kilmer, co-founder of Spur.us, a startup that tracks criminal proxy services. Kilmer said RSOCKS was similarly disabled after Google’s combined legal sneak attack and technical takedown targeting Glupteba.

“The RSOCKS website gave you the estimated number of proxies in each of their subscription packages, and that number went down to zero on Dec. 7,” Kilmer said. “It’s not clear if that means the services were operated by the same people, or if they were just using the same sources (i.e., PPI programs) to generate new installations of their malware.”

Kilmer said each time his company tried to determine how many systems RSOCKS had for sale, they found each Internet address being sold by RSOCKS was also present in AWM Proxy’s network. In addition, Kilmer said, the application programming interfaces (APIs) used by both services to keep track of infected systems were virtually identical, once again suggesting strong collaboration.

“One hundred percent of the IPs we got back from RSOCKS we’d already identified in AWM,” Kilmer said. “And the IP port combinations they give you when you access an individual IP were the same as from AWM.”

In 2011, KrebsOnSecurity published an investigation that identified one of the founders of AWM Proxy, but Kilmer’s revelation prompted me to take a fresh look at the origins of this sprawling cybercriminal enterprise to determine if there were additional clues showing more concrete links between RSOCKS, AWM Proxy and Glupteba.

IF YOUR PLAN IS TO RIP OFF GOOGLE…

Supporting Kilmer’s theory that AWM Proxy and RSOCKS may simply be using the same PPI networks to spread, further research shows the RSOCKS owner also had an ownership stake in AD1[.]ru, an extremely popular Russian-language pay-per-install network that has been in operation for at least a decade.

Google took aim at Glupteba in part because its owners were using the botnet to divert and steal vast sums in online advertising revenue. So it’s more than a little ironic that the critical piece of evidence linking all of these operations begins with a Google Analytics code included in the HTML code for the original AWM Proxy back in 2008 (UA-3816536).

That analytics code also was present on a handful of other sites over the years, including the now-defunct Russian domain name registrar Domenadom[.]ru, and the website web-site[.]ru, which curiously was a Russian company operating a global real estate appraisal business called American Appraisal.

Two other domains connected to that Google Analytics code — Russian plastics manufacturers techplast[.]ru and tekhplast.ru — also shared a different Google Analytics code (UA-1838317) with web-site[.]ru and with the domain “starovikov[.]ru.”

The name on the WHOIS registration records for the plastics domains is an “Alexander I. Ukraincki,” whose personal information also is included in the domains tpos[.]ru and alphadisplay[.]ru, both apparently manufacturers of point-of-sale payment terminals in Russia.

Constella Intelligence, a security firm that indexes passwords and other personal information exposed in past data breaches, revealed dozens of variations on email addresses used by Alexander I. Ukraincki over the years. Most of those email addresses start with some variation of “uai@” followed by a domain from one of the many Russian email providers (e.g., yandex.ru, mail.ru). [Full disclosure: Constella is currently an advertiser on this website].

But Constella also shows those different email addresses all relied on a handful of passwords — most commonly “2222den” and “2222DEN.” Both of those passwords have been used almost exclusively in the past decade by the person who registered more than a dozen email addresses with the username “dennstr.”

The dennstr identity leads to several variations on the same name — Denis Strelinikov, or Denis Stranatka, from Ukraine, but those clues ultimately led nowhere promising. And maybe that was the point.

Things began looking brighter after I ran a search in DomainTools for web-site[.]ru’s original WHOIS records, which shows it was assigned in 2005 to a “private person” who used the email address lycefer@gmail.com. A search in Constella on that email address says it was used to register nearly two dozen domains, including starovikov.ru and starovikov[.]com.

A cached copy of the contact page for Starovikov[.]com shows that in 2008 it displayed the personal information for a Dmitry Starovikov, who listed his Skype username as “lycefer.”

Finally, Russian incorporation documents show the company LLC Website (web-site[.]ru)was registered in 2005 to two men, one of whom was named Dmitry Sergeevich Starovikov.

Bringing this full circle, Google says Starovikov is one of the two operators of the Glupteba botnet:

Mr. Starovikov did not respond to requests for comment. But attorneys for Starovikov and his co-defendant last month filed a response to Google’s complaint in the Southern District of New York, denying (PDF) their clients had any knowledge of the scheme.

Despite all of the disruption caused by Google’s legal and technical meddling, AWM is still around and nearly as healthy as ever, although the service has been branded with a new name and there are dubious claims of new owners. Advertising customer plans ranging from $50 a day to nearly $700 for “VIP access,” AWM Proxy says its malware has been running on approximately 175,000 systems worldwide over the last 24 hours, and that roughly 65,000 of these systems are currently online.

Meanwhile, the administrators of RSOCKS recently alerted customers that the service and any unspent balances will soon be migrated over to a new location.

Many people seem to equate spending time, money and effort to investigate and prosecute cybercriminals with the largely failed war on drugs, meaning there is an endless supply of up-and-coming crooks who will always fill in any gaps in the workforce whenever cybercriminals face justice.

While that may be true for many low-level cyber thieves today, investigations like these show once again how small the cybercriminal underground really is. It also shows how it makes a great deal of sense to focus efforts on targeting and disrupting the relatively small number of established hackers who remain the real force multipliers of cybercrime.