Dviros (6)

Last Login: August 23, 2021

Dviros's Contributions (2)

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Technical Analysis

As Cobalt Strike’s source code got leaked in November 2020, it seems that versions 4.2 and 4.3 are both vulnerable to a Denial of Service attack that occurs when a new beacon registers with the Teamserver, thus causing a memory load and server crash.
The attacker need to the know the relevant beacon configuration prior to the execution, but this can be done rather easily with a multitude of tools released over GitHub, that performs config extraction from known Cobalt Strike C2 servers.
Cobalt Strike has become a tool which is used commonly by different threat actor groups worldwide, due to its availability, capabilities and effectiveness in covert channels.

Sentinel One have researched, reported and released a PoC code that triggers this vulnerability:

As the PoC code got released, it is safe to assume that vulnerable C2 servers worldwide are being attacked.

To fix this issue, version 4.4 was released.

Technical Analysis

Vulnerability is easy to exploit – by interacting with the local ShadowCopy volume, and copying it to a local folder, attackers can easily elevate their privileges.
Several exploits were already released, allowing to parse the hashes while copying the SAM\SECURITY\SYSTEM hives:

This vulnerability occurs due to the permissive “C:\Windows\System32\Config*.*” privileges, “BUILTIN\Users”, allowing any user to read and execute the files.