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Before yesterdayKrebs on Security

Tourists Give Themselves Away by Looking Up. So Do Most Network Intruders.

In large metropolitan areas, tourists are often easy to spot because they’re far more inclined than locals to gaze upward at the surrounding skyscrapers. Security experts say this same tourist dynamic is a dead giveaway in virtually all computer intrusions that lead to devastating attacks like data theft and ransomware, and that more organizations should set simple virtual tripwires that sound the alarm when authorized users and devices are spotted exhibiting this behavior.

In a blog post published last month, Cisco Talos said it was seeing a worrisome “increase in the rate of high-sophistication attacks on network infrastructure.” Cisco’s warning comes amid a flurry of successful data ransom and state-sponsored cyber espionage attacks targeting some of the most well-defended networks on the planet.

But despite their increasing complexity, a great many initial intrusions that lead to data theft could be nipped in the bud if more organizations started looking for the telltale signs of newly-arrived cybercriminals behaving like network tourists, Cisco says.

“One of the most important things to talk about here is that in each of the cases we’ve seen, the threat actors are taking the type of ‘first steps’ that someone who wants to understand (and control) your environment would take,” Cisco’s Hazel Burton wrote. “Examples we have observed include threat actors performing a ‘show config,’ ‘show interface,’ ‘show route,’ ‘show arp table’ and a ‘show CDP neighbor.’ All these actions give the attackers a picture of a router’s perspective of the network, and an understanding of what foothold they have.”

Cisco’s alert concerned espionage attacks from China and Russia that abused vulnerabilities in aging, end-of-life network routers. But at a very important level, it doesn’t matter how or why the attackers got that initial foothold on your network.

It might be zero-day vulnerabilities in your network firewall or file-transfer appliance. Your more immediate and primary concern has to be: How quickly can you detect and detach that initial foothold?

The same tourist behavior that Cisco described attackers exhibiting vis-a-vis older routers is also incredibly common early on in ransomware and data ransom attacks — which often unfurl in secret over days or weeks as attackers methodically identify and compromise a victim’s key network assets.

These virtual hostage situations usually begin with the intruders purchasing access to the target’s network from dark web brokers who resell access to stolen credentials and compromised computers. As a result, when those stolen resources first get used by would-be data thieves, almost invariably the attackers will run a series of basic commands asking the local system to confirm exactly who and where they are on the victim’s network.

This fundamental reality about modern cyberattacks — that cybercriminals almost always orient themselves by “looking up” who and where they are upon entering a foreign network for the first time — forms the business model of an innovative security company called Thinkst, which gives away easy-to-use tripwires or “canaries” that can fire off an alert whenever all sorts of suspicious activity is witnessed.

“Many people have pointed out that there are a handful of commands that are overwhelmingly run by attackers on compromised hosts (and seldom ever by regular users/usage),” the Thinkst website explains. “Reliably alerting when a user on your code-sign server runs whoami.exe can mean the difference between catching a compromise in week-1 (before the attackers dig in) and learning about the attack on CNN.”

These canaries — or “canary tokens” — are meant to be embedded inside regular files, acting much like a web beacon or web bug that tracks when someone opens an email.

The Canary Tokens website from Thinkst Canary lists nearly two-dozen free customizable canaries.

“Imagine doing that, but for file reads, database queries, process executions or patterns in log files,” the Canary Tokens documentation explains. “Canarytokens does all this and more, letting you implant traps in your production systems rather than setting up separate honeypots.”

Thinkst operates alongside a burgeoning industry offering so-called “deception” or “honeypot” services — those designed to confuse, disrupt and entangle network intruders. But in an interview with KrebsOnSecurity, Thinkst founder and CEO Haroon Meer said most deception techniques involve some degree of hubris.

“Meaning, you’ll have deception teams in your network playing spy versus spy with people trying to break in, and it becomes this whole counterintelligence thing,” Meer said. “Nobody really has time for that. Instead, we are saying literally the opposite: That you’ve probably got all these [security improvement] projects that are going to take forever. But while you’re doing all that, just drop these 10 canaries, because everything else is going to take a long time to do.”

The idea here is to lay traps in sensitive areas of your network or web applications where few authorized users should ever trod. Importantly, the canary tokens themselves are useless to an attacker. For example, that AWS canary token sure looks like the digital keys to your cloud, but the token itself offers no access. It’s just a lure for the bad guys, and you get an alert when and if it is ever touched.

One nice thing about canary tokens is that Thinkst gives them away for free. Head over to canarytokens.org, and choose from a drop-down menu of available tokens, including:

-a web bug / URL token, designed to alert when a particular URL is visited;
-a DNS token, which alerts when a hostname is requested;
-an AWS token, which alerts when a specific Amazon Web Services key is used;
-a “custom exe” token, to alert when a specific Windows executable file or DLL is run;
-a “sensitive command” token, to alert when a suspicious Windows command is run.
-a Microsoft Excel/Word token, which alerts when a specific Excel or Word file is accessed.

Much like a “wet paint” sign often encourages people to touch a freshly painted surface anyway, attackers often can’t help themselves when they enter a foreign network and stumble upon what appear to be key digital assets, Meer says.

“If an attacker lands on your server and finds a key to your cloud environment, it’s really hard for them not to try it once,” Meer said. “Also, when these sorts of actors do land in a network, they have to orient themselves, and while doing that they are going to trip canaries.”

Meer says canary tokens are as likely to trip up attackers as they are “red teams,” security experts hired or employed by companies seeking to continuously probe their own computer systems and networks for security weaknesses.

“The concept and use of canary tokens has made me very hesitant to use credentials gained during an engagement, versus finding alternative means to an end goal,” wrote Shubham Shah, a penetration tester and co-founder of the security firm Assetnote. “If the aim is to increase the time taken for attackers, canary tokens work well.”

Thinkst makes money by selling Canary Tools, which are honeypots that emulate full blown systems like Windows servers or IBM mainframes. They deploy in minutes and include a personalized, private Canarytoken server.

“If you’ve got a sophisticated defense team, you can start putting these things in really interesting places,” Meer said. “Everyone says their stuff is simple, but we obsess over it. It’s really got to be so simple that people can’t mess it up. And if it works, it’s the best bang for your security buck you’re going to get.”

Further reading:

Dark Reading: Credential Canaries Create Minefield for Attackers
NCC Group: Extending a Thinkst Canary to Become an Interactive Honeypot
Cruise Automation’s experience deploying canary tokens

Apple & Microsoft Patch Tuesday, July 2023 Edition

Microsoft Corp. today released software updates to quash 130 security bugs in its Windows operating systems and related software, including at least five flaws that are already seeing active exploitation. Meanwhile, Apple customers have their own zero-day woes again this month: On Monday, Apple issued (and then quickly pulled) an emergency update to fix a zero-day vulnerability that is being exploited on MacOS and iOS devices.

On July 10, Apple pushed a “Rapid Security Response” update to fix a code execution flaw in the Webkit browser component built into iOS, iPadOS, and macOS Ventura. Almost as soon as the patch went out, Apple pulled the software because it was reportedly causing problems loading certain websites. MacRumors says Apple will likely re-release the patches when the glitches have been addressed.

Launched in May, Apple’s Rapid Security Response updates are designed to address time-sensitive vulnerabilities, and this is the second month Apple has used it. July marks the sixth month this year that Apple has released updates for zero-day vulnerabilities — those that get exploited by malware or malcontents before there is an official patch available.

If you rely on Apple devices and don’t have automatic updates enabled, please take a moment to check the patch status of your various iDevices. The latest security update that includes the fix for the zero-day bug should be available in iOS/iPadOS 16.5.1, macOS 13.4.1, and Safari 16.5.2.

On the Windows side, there are at least four vulnerabilities patched this month that earned high CVSS (badness) scores and that are already being exploited in active attacks, according to Microsoft. They include CVE-2023-32049, which is a hole in Windows SmartScreen that lets malware bypass security warning prompts; and CVE-2023-35311 allows attackers to bypass security features in Microsoft Outlook.

The two other zero-day threats this month for Windows are both privilege escalation flaws. CVE-2023-32046 affects a core Windows component called MSHTML, which is used by Windows and other applications, like Office, Outlook and Skype. CVE-2023-36874 is an elevation of privilege bug in the Windows Error Reporting Service.

Many security experts expected Microsoft to address a fifth zero-day flaw — CVE-2023-36884 — a remote code execution weakness in Office and Windows.

“Surprisingly, there is no patch yet for one of the five zero-day vulnerabilities,” said Adam Barnett, lead software engineer at Rapid7. “Microsoft is actively investigating publicly disclosed vulnerability, and promises to update the advisory as soon as further guidance is available.”

Barnett notes that Microsoft links exploitation of this vulnerability with Storm-0978, the software giant’s name for a cybercriminal group based out of Russia that is identified by the broader security community as RomCom.

“Exploitation of CVE-2023-36884 may lead to installation of the eponymous RomCom trojan or other malware,” Barnett said. “[Microsoft] suggests that RomCom / Storm-0978 is operating in support of Russian intelligence operations. The same threat actor has also been associated with ransomware attacks targeting a wide array of victims.”

Microsoft’s advisory on CVE-2023-36884 is pretty sparse, but it does include a Windows registry hack that should help mitigate attacks on this vulnerability. Microsoft has also published a blog post about phishing campaigns tied to Storm-0978 and to the exploitation of this flaw.

Barnett said it’s while it’s possible that a patch will be issued as part of next month’s Patch Tuesday, Microsoft Office is deployed just about everywhere, and this threat actor is making waves.

“Admins should be ready for an out-of-cycle security update for CVE-2023-36884,” he said.

Microsoft also today released new details about how it plans to address the existential threat of malware that is cryptographically signed by…wait for it….Microsoft.

In late 2022, security experts at Sophos, Trend Micro and Cisco warned that ransomware criminals were using signed, malicious drivers in an attempt to evade antivirus and endpoint detection and response (EDR) tools.

In a blog post today, Sophos’s Andrew Brandt wrote that Sophos identified 133 malicious Windows driver files that were digitally signed since April 2021, and found 100 of those were actually signed by Microsoft. Microsoft said today it is taking steps to ensure those malicious driver files can no longer run on Windows computers.

As KrebsOnSecurity noted in last month’s story on malware signing-as-a-service, code-signing certificates are supposed to help authenticate the identity of software publishers, and provide cryptographic assurance that a signed piece of software has not been altered or tampered with. Both of these qualities make stolen or ill-gotten code-signing certificates attractive to cybercriminal groups, who prize their ability to add stealth and longevity to malicious software.

Dan Goodin at Ars Technica contends that whatever Microsoft may be doing to keep maliciously signed drivers from running on Windows is being bypassed by hackers using open source software that is popular with video game cheaters.

“The software comes in the form of two software tools that are available on GitHub,” Goodin explained. “Cheaters use them to digitally sign malicious system drivers so they can modify video games in ways that give the player an unfair advantage. The drivers clear the considerable hurdle required for the cheat code to run inside the Windows kernel, the fortified layer of the operating system reserved for the most critical and sensitive functions.”

Meanwhile, researchers at Cisco’s Talos security team found multiple Chinese-speaking threat groups have repurposed the tools—one apparently called “HookSignTool” and the other “FuckCertVerifyTimeValidity.”

“Instead of using the kernel access for cheating, the threat actors use it to give their malware capabilities it wouldn’t otherwise have,” Goodin said.

For a closer look at the patches released by Microsoft today, check out the always-thorough Patch Tuesday roundup from the SANS Internet Storm Center. And it’s not a bad idea to hold off updating for a few days until Microsoft works out any kinks in the updates: AskWoody.com usually has the lowdown on any patches that may be causing problems for Windows users.

And as ever, please consider backing up your system or at least your important documents and data before applying system updates. If you encounter any problems with these updates, please drop a note about it here in the comments.

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