Hackers are exploiting a server vulnerability with a severity of 9.8 out of 10

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In a growth safety professionals feared, attackers are actively focusing on yet one more set of important server vulnerabilities that depart companies and governments open to severe community intrusions.

The vulnerability this time is in BIG-IP, a line of server home equipment offered by Seattle-based F5 Networks. Prospects use BIG-IP servers to handle visitors going into and out of enormous networks. Duties embrace load balancing, DDoS mitigation, and internet utility safety.

Final week, F5 disclosed and patched important BIG-IP vulnerabilities that permit hackers to achieve full management of a server. Regardless of a severity ranking of 9.8 out of 10, the safety flaws bought overshadowed by a special set of important vulnerabilities Microsoft disclosed and patched in Alternate server per week earlier. Inside just a few days of Microsoft’s emergency replace, tens of hundreds of Alternate servers within the US had been compromised.

Day of reckoning

When safety researchers weren’t busy attending to the unfolding Alternate mass compromise, lots of them warned that it was solely a matter of time earlier than the F5 vulnerabilities additionally got here below assault. Now, that day has come.

Researchers at safety agency NCC Group on Friday said they’re “seeing full chain exploitation” of CVE-2021-22986, a vulnerability that permits distant attackers with no password or different credentials to execute instructions of their alternative on susceptible BIG-IP units.

“After seeing numerous damaged exploits and failed makes an attempt, we are actually seeing profitable within the wild exploitation of this vulnerability, as of this morning,” Wealthy Warren, Principal Safety Marketing consultant at NCC Group and co-author of the weblog wrote.

In a weblog put up NCC Group posted a screenshot displaying exploit code that might efficiently steal an authenticated session token, which is a kind of browser cookie that permits directors to make use of a web-based programming interface to remotely management BIG-IP {hardware}.

NCC Group

“The attackers are hitting a number of honeypots in several areas, suggesting that there isn’t any particular focusing on,” Warren wrote in an electronic mail. “It’s extra possible that they’re ‘spraying’ makes an attempt throughout the web, within the hope that they will exploit the vulnerability earlier than organizations have an opportunity to patch it.”

He stated that earlier makes an attempt used incomplete exploits that had been derived from the restricted info that was accessible publicly.

Safety agency Palo Alto Networks, in the meantime, said that CVE-2021-22986 was being focused by a units contaminated with a variant of the open-source Mirai malware. The tweet stated the variant was “making an attempt to use” the vulnerability, however it wasn’t clear if the makes an attempt had been profitable.

Different researchers reported Web-wide scans designed to find BIG-IP servers which can be susceptible.

CVE-2021-22986 is just one of a number of important BIG-IP vulnerabilities F5 disclosed and patched final week. The severity Partly is as a result of the vulnerabilities require restricted talent to use. However extra importantly, as soon as attackers have management of a BIG-IP server, they’re kind of contained in the safety perimeter of the community utilizing it. Which means attackers can shortly entry different delicate elements of the community.

As if admins didn’t have already got sufficient to take care of, patching susceptible BIG-IP servers and searching for exploits needs to be a high precedence. NCC Group supplied indicators of compromise within the hyperlink above, and Palo Alto Networks has IOCs here.

Replace: After this put up went stay, F5 issued an announcement. It learn: “We’re conscious of assaults focusing on latest vulnerabilities revealed by F5. As with all important vulnerabilities, we advise clients replace their methods as quickly as doable.”

In the meantime, NCC Group’s Wealthy Warren responded to questions I despatched earlier. This is a partial Q&A:

What does “seeing full chain exploitation” imply? What was NCC Group seeing earlier than, and the way does “full chain exploitation” change it?

What we imply is that, beforehand we had been seeing attackers making an attempt to abuse the SSRF vulnerability in a method which couldn’t work, as a result of an necessary a part of the exploit was not public data, subsequently the exploits would fail. Now, attackers have found out the complete particulars wanted to make use of the SSRF to bypass authentication and acquire authentication tokens. These authentication tokens can then be used to execute instructions remotely. Up to now, we now have seen the attackers a) receive an authentication token, and b) execute instructions to dump credentials. We have not seen any web-shells being dropped like we did with CVE-2020-5902, but.

The place, exactly, are you seeing the exploit makes an attempt? Is it in a honeypot, on manufacturing servers, some place else?

The attackers are hitting a number of honeypots in several areas, suggesting that there isn’t any particular focusing on. It’s extra possible that they’re “spraying” makes an attempt throughout the web, within the hope that they will exploit the vulnerability earlier than organizations have an opportunity to patch it. Earlier makes an attempt we noticed in opposition to our honeypot infrastructure confirmed that attackers had been utilizing incomplete exploits based mostly on restricted info that was accessible within the public area. This exhibits that attackers are clearly eager to use the vulnerability – even when a few of them do not have the requisite data to engineer their very own assault code.

Are you aware if the exploits are succeeding in compromising manufacturing servers? If sure, what are attackers doing put up exploitation?

For the time being we will not touch upon whether or not the identical attackers have been profitable in opposition to different folks’s servers. Close to post-exploitation actions, we now have solely seen credential dumping to this point.

I am studying that a number of risk teams are exploiting the vulnerability. Are you aware this to be true? If that’s the case, what number of totally different risk actors are there?

We have not acknowledged that there are a number of attackers. In truth, whereas we have seen a number of profitable exploitation makes an attempt from totally different IPs, all makes an attempt have contained some particular hallmarks that are in step with the opposite makes an attempt, suggesting it is possible the identical underlying exploit.

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