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

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

The vulnerability this time is in BIG-IP, a line of server home equipment bought by Seattle-based F5 Networks. Clients use BIG-IP servers to handle visitors going into and out of huge networks. Duties embody load balancing, DDoS mitigation, and internet software safety.

Final week, F5 disclosed and patched important BIG-IP vulnerabilities that permit hackers to realize full management of a server. Regardless of a severity ranking of 9.8 out of 10, the safety flaws obtained overshadowed by a unique 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 1000’s of Alternate servers within the US have 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 underneath 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 selection on susceptible BIG-IP units.

“After seeing plenty of 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 submit NCC Group posted a screenshot displaying exploit code that would 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 a particular focusing on,” Warren wrote in an electronic mail. “It’s extra seemingly that they’re ‘spraying’ makes an attempt throughout the web, within the hope that they’ll exploit the vulnerability earlier than organizations have an opportunity to patch it.”

He mentioned that earlier makes an attempt used incomplete exploits that have 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 mentioned the variant was “trying to use” the vulnerability, however it wasn’t clear if the makes an attempt have been profitable.

Different researchers reported Web-wide scans designed to find BIG-IP servers which might 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 roughly contained in the safety perimeter of the community utilizing it. Meaning attackers can shortly entry different delicate elements of the community.

As if admins did not have already got sufficient to take care of, patching susceptible BIG-IP servers and in search of exploits ought to be a high precedence. NCC Group offered indicators of compromise within the hyperlink above, and Palo Alto Networks has IOCs here.

Replace 8:22 pm EDT: After this submit went dwell, F5 issued a press release. It learn: “We’re conscious of assaults focusing on latest vulnerabilities revealed by F5. As with all important vulnerabilities, we advise prospects 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 have been seeing attackers trying to abuse the SSRF vulnerability in a means which couldn’t work, as a result of an vital a part of the exploit was not public data, subsequently the exploits would fail. Now, attackers have discovered the total 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. Thus far, we’ve got seen the attackers a) get hold of an authentication token, and b) execute instructions to dump credentials. We’ve 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, someplace else?
The attackers are hitting a number of honeypots in several areas, suggesting that there isn’t a particular focusing on. It’s extra seemingly that they’re “spraying” makes an attempt throughout the web, within the hope that they’ll exploit the vulnerability earlier than organizations have an opportunity to patch it. Earlier makes an attempt we noticed towards our honeypot infrastructure confirmed that attackers have 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.

Have you learnt if the exploits are succeeding in compromising manufacturing servers? If sure, what are attackers doing post-exploitation?

For the time being, we will not touch upon whether or not the identical attackers have been profitable towards different folks’s servers. With reference to post-exploitation actions, we’ve got solely seen credential dumping thus far.

I am studying that a number of menace teams are exploiting the vulnerability. Have you learnt this to be true? In that case, what number of completely different menace actors are there?

We have not said that there are a number of attackers. Actually, whereas we have seen a number of profitable exploitation makes an attempt from completely different IPs, all makes an attempt have contained some particular hallmarks that are in keeping with the opposite makes an attempt, suggesting it is seemingly the identical underlying exploit.

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