Multiple path traversal vulnerabilities exist in smbserver.py in Impacket before 0.9.23. An attacker that connects to a running smbserver instance can list and write to arbitrary files via ../ directory traversal. This could potentially be abused to achieve arbitrary code execution by replacing /etc/shadow or an SSH authorized key.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-31800
• fortra/impacket@49c643b
• https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L2008
• https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L2958
• https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L3485
• https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L876
• https://github.com/SecureAuthCorp/impacket/releases
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/IPXDPWCAPVX3UWYZ3N2T5OLBSBBUHJP6/
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/KRV2C5DATXBHG6TF6CEEX54KZ75THQS3/
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UF56LYB27LHEIFJTFHU3M75NMNNK2SCG/
• fortra/impacket@99bd29e
• https://github.com/SecureAuthCorp/impacket/releases/tag/impacket_0_9_23