Microsoft is working on patches for a critical remote code execution vulnerability in Server Message Block 3.0 (SMBv3) that exposes systems to “wormable” attacks.
According to Microsoft, the vulnerability is related to the way SMB 3.1.1 handles certain requests and it can be exploited by an unauthenticated attacker to execute arbitrary code on SMB servers and clients.
In attacks aimed at SMB servers, the attacker needs to send specially crafted packets to the targeted system. In the case of client attacks, the hacker needs to convince the targeted user to connect to a malicious SMBv3 server.
Some have dubbed the vulnerability CoronaBlue, while others call it SMBGhost.
Microsoft published an advisory for this vulnerability, which it tracks as CVE-2020-0796, when it announced the Patch Tuesday updates for March. However, the advisory was quickly removed as a fix has yet to be released.
The now-removed advisory warned that “exploitation of this vulnerability opens systems up to a ‘wormable’ attack, which means it would be easy to move from victim to victim.”
Microsoft has published a different advisory recommending that users disable SMBv3 compression until a patch is released. Users can also mitigate the risk by blocking TCP port 445 on perimeter firewalls, but this would still allow attacks to be launched from within the network. Users can also follow Microsoft’s guidelines for preventing SMB traffic from leaving the corporate network.