Privilege escalation in Windows and Windows Server - CVE-2018-8440
Published: August 28, 2018 / Updated: September 11, 2018
Vulnerability identifier: #VU14547
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Green
CVE-ID: CVE-2018-8440
CWE-ID: CWE-264
Exploitation vector: Local access
Exploit availability:
The vulnerability is being exploited in the wild
Vendor: Microsoft
Affected software:
Windows
Windows Server
Windows
Windows Server
Detailed vulnerability description
The vulnerability allows a local attacker to gain elevated privileges on the target system.
The vulnerability exists due to ALPC access control flaw. A local attacker can create a hard link from a readable file on the system to a '.job' file in the 'c:\windows\tasks' directory, invoke the _SchRpcSetSecurity() method of the task scheduler service ALPC endpoint to overwrite the linked file and gain system level privileges on the target system. The vulnerability was dubbed "SendboxEscaper".
Note: the vulnerability is being exploited in the wild by the PowerPool group.
How to mitigate CVE-2018-8440
Install update from vendor's website.
Sources
- https://twitter.com/SandboxEscaper/status/1034125195148255235
- https://github.com/SandboxEscaper/randomrepo/blob/master/PoC-LPE.rar
- https://www.kb.cert.org/vuls/id/906424
- https://www.welivesecurity.com/2018/09/05/powerpool-malware-exploits-zero-day-vulnerability/
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2018-8440