APTs are exploiting CVE-2020
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2020-0688 | RCE in Microsoft Exchange Server from Shared Install-Time Validation Keys CVE-2020-0688 is a remote code execution vulnerability in Microsoft Exchange Server caused by the validation key not being uniquely created at install time, leaving deployments with a predictable, shared key (CWE-287, improper authentication). A remote attacker who can reach an affected Exchange server and knows the common install-time key can supply maliciously crafted, cryptographically signed payloads that the server trusts, triggering code execution without needing per-server secrets. Successful exploitation gives the attacker code execution on the Exchange server, which can be used to access mail data, move laterally, and stage follow-on activity; CISA notes known use in ransomware campaigns. All organizations running the affected on-premises Microsoft Exchange Server are in scope per CISA's listing, though the affected version range is not specified in the source data. Exploitation is confirmed in the wild: the flaw was added to CISA's KEV on 2021-11-03 with known ransomware use, and EPSS rates 30-day exploitation probability at 100% (top percentile). Do: Apply Microsoft's Exchange security updates addressing CVE-2020-0688 (released in February 2020) to every on-premises Exchange server, per CISA's required action. As an interim mitigation, configure a unique ASP.NET machineKey in each Exchange server's web.config instead of the default shared install-time key, and hunt for indicators of exploitation given the known ransomware use. | 8.8 | 100% | KEV ransomware PoC ×2 |
| masshundreds of thousands of on-premises Exchange servers (≈500,000) |
Full article538 words · extracted from securityaffairs.com · click to collapse
Multiple state-sponsored hacking groups are attempting to exploit a vulnerability recently addressed in Microsoft Exchange email servers.
Cybersecurity firm Volexity is warning that nation-state actors are attempting to exploit a vulnerability recently addressed in Microsoft Exchange email servers tracked as CVE-2020-0688.
The experts did not provide details on the threat actors that are exploiting the vulnerability, according ZDNet that cited a DOD source the attackers belong to prominent APT groups.
The CVE-2020-0688 flaw resides in the Exchange Control Panel (ECP) component, the root cause of the problem is that Exchange servers fail to properly create unique keys at install time.
“Knowledge of a the validation key allows an authenticated user with a mailbox to pass arbitrary objects to be deserialized by the web application, which runs as SYSTEM.” reads the advisory published by Microsoft.
A remote, authenticated attacker could exploit the CVE-2020-0688 vulnerability to execute arbitrary code with SYSTEM privileges on a server and take full control.
Security experts Simon Zuckerbraun from Zero Day Initiative published technical details on how to exploit the Microsoft Exchange CVE-2020-0688 along with a video PoC.
“Similarly, any outside attacker who compromised the device or credentials of any enterprise user would be able to proceed to take over the Exchange server. Having accomplished this, an attacker would be positioned to divulge or falsify corporate email communications at will.” wrote Zuckerbraun. “Accordingly, if you’re an Exchange Server administrator, you should treat this as a Critical-rated patch and deploy it as soon as your testing is complete. Microsoft lists this with an Exploit Index of 1, which means they expect to see exploits within 30 days of the patch release.”
A couple of weeks ago, the popular security researcher Kevin Beaumont reported mass scanning for the CVE-2020-0688 (Microsoft Exchange 2007+ RCE vulnerability).
https://twitter.com/GossiTheDog/status/1232430811439403014
In the same period, experts at Bad Packets confirmed an ongoing scanning activity.
https://twitter.com/bad_packets/status/1232428319733272579
Microsoft released security updates for the CVE-2020-0688 flaw on February 11, at the time experts urged administrators to patch their servers before attackers could reach them and exploit the issue.
Since the disclosure of the flaw, at least three of proof-of-concept exploit codes were released online [1, 2, 3] and nation-state actors started using them in the wild.
APT groups are interested in hacking Microsoft exchange servers to intercept and read the company’s email traffic.
“Volexity has observed multiple APT actors exploiting or attempting to exploit on-premise Exchange servers. In some cases the attackers appear to have been waiting for an opportunity to strike with credentials that had otherwise been of no use.” reads the analysis published by Volexity. “Volexity has also observed multiple concerted efforts by APT groups to brute-force credentials by leveraging Exchange Web Services (EWS) in an effort to likely exploit this vulnerability. While brute-forcing credentials is a common occurrence, the frequency and intensity of attacks at certain organizations has increased dramatically following the vulnerability disclosure.”
The good news is that the CVE-2020-0688 Exchange vulnerability is not easy to exploit because the attackers first need to be authenticated to the target system then run malware to trigger the issue and hijack the victim’s email server.
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(SecurityAffairs – hacking, CVE-2020-0688)
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Text extracted automatically; images, tables and formatting may be missing. Original: https://securityaffairs.com/99214/hacking/hackers-cve-2020-0688-microsoft-exchange.html