10 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
7.5 High
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
0.975 High
EPSS
Percentile
100.0%
Microsoft SMBv3 contains a vulnerability in the handling of compression, which may allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system. This vulnerability is being referred to as βSMBGhost and CoronaBlue.β
Microsoft Server Message Block 3.1.1 (SMBv3) contains a vulnerability in the way that it handles connections that use compression. This vulnerability may allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system. It has been reported that this vulnerability is βwormable.β
By connecting to a vulnerable Windows machine using SMBv3, or by causing a vulnerable Windows system to initiate a client connection to a SMBv3 server, a remote, unauthenticated attacker may be able to execute arbitrary code with SYSTEM privileges on a vulnerable system.
Apply an update
This issue has been addressed in the Microsoft update for CVE-2020-0796. Please also consider the following workarounds:
Disable SMBv3 compression
According to Microsoft Security Advisory ADV200005 :
You can disable compression to block unauthenticated attackers from exploiting the vulnerability against an SMBv3 Server with the PowerShell command below.
_Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters" DisableCompression -Type DWORD -Value 1 -Force_
Notes:
1. No reboot is needed after making the change.
2. This workaround does not prevent exploitation of SMB clients.
You can disable the workaround with the PowerShell command below.
_Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters" DisableCompression -Type DWORD -Value 0 -Force_
Block inbound and outbound SMB
Consider blocking outbound SMB connections (TCP port 445 for SMBv3) from the local network to the WAN. Also ensure that SMB connections from the internet are not allowed to connect inbound to an enterprise LAN.
This document was written by Will Dormann.
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Updated: 2020-06-19 CVE-2020-0796 | Affected |
---|
We have not received a statement from the vendor.
Group | Score | Vector |
---|---|---|
Base | 10 | AV:N/AC:L/Au:N/C:C/I:C/A:C |
Temporal | 7.8 | E:POC/RL:OF/RC:C |
Environmental | 7.8 | CDP:ND/TD:ND/CR:ND/IR:ND/AR:ND |
CVE IDs: | CVE-2020-0796 |
---|---|
Date Public: | 2020-03-10 Date First Published: |
10 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
7.5 High
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
0.975 High
EPSS
Percentile
100.0%