Bitvise SSH Server 9.32 [ 20 December 2023 ]
- Version information:
- This version continues the upgrade access amnesty introduced in version 9.25, so it can be used with any license that is valid for a previous SSH Server 9.xx version. The minimum upgrade access expiry date to activate this version is January 1, 2022.
- You can
Zaloguj lub Zarejestruj się aby zobaczyć!. (Zaloguj lub Zarejestruj się aby zobaczyć!)- Security:
- Terrapin -
Zaloguj lub Zarejestruj się aby zobaczyć!: Researchers have identified an issue where all SSH connections which use the encryption algorithm ChaCha20-Poly1305, or any integrity algorithm of type encrypt-then-MAC, are vulnerable to packet sequence manipulation by an active attacker, if the attacker can intercept the network path. This can be used to sabotage SSH extension negotiation. This affects extensions with security impact, such as server-sig-algs.
Since the attacker can only remove packets sent before user authentication, this does not seem to fatally break the security of the SSH connection. However, it is a cryptographic weakness to address.
Bitvise software versions 9.32 and newer support strict key exchange. This is a new SSH protocol feature which mitigates this attack. The SSH client and server must both implement strict key exchange for mitigation to be effective. Other SSH software authors are also releasing new versions to support this.
If you must interoperate with SSH software which does not support strict key exchange, consider disabling the encryption algorithm ChaCha20-Poly1305, as well as integrity algorithms of type encrypt-then-MAC. These are the newer data integrity protection algorithms whose names contain -etm.
Bitvise software versions 8.xx and older are not substantially affected because they do not implement algorithms where this issue is practically exploitable. Nevertheless, we suggest updating all SSH software to new versions that support strict key exchange.
The encryption algorithms aes256-gcm and aes128-gcm are substantially immune from this attack. Users who are committed to older SSH software versions should consider using AES GCM. If this is not possible, the data integrity protection algorithms which are not named -etm are not entirely immune, but are also not believed to be practically exploitable. For compatibility with SSH software which does not support strict key exchange or AES GCM, an algorithm combination such as AES CTR with non-ETM data integrity protection may continue to be acceptable.- General:
- If the SSH Server was configured to accept FTPS connections, but no certificate was employed; or if the employed certificate was not usable because it expired; the SSH Server would stop running and refuse to start, even for SSH connections, until the administrator fixed the certificate issue.
The SSH Server will now start, and continue running, as long as the configuration allows connections to be handled on at least one SSH or FTPS binding.- SSH:
- When a user authentication banner is entered directly in SSH Server settings, the SSH Server will no longer strip leading and trailing whitespace. If the banner does not end with a newline, the SSH Server will now append it. This avoids OpenSSH displaying the last line incorrectly.
- Email notifications:
- Further improved error messages when SMTP sending fails.
- Settings:
- When a list of address accept rules was imported from CSV using the options Import blocked IPs or Import permitted IPs, IP address ranges were imported incorrectly. Fixed.
- File transfer:
- When using a mount point of type Another SFTP server, the other SFTP server may support SFTP protocol version 5 or higher, but not SFTP v5+ file locking. In this case, the SSH Server now strips file open block flags sent by the client if the block flags include SSH_FXF_BLOCK_ADVISORY.
As in previous versions, it is possible to always strip block flags by configuring mount point settings:
File sharing behavior: Force File sharing for uploads: Read, Write, Delete File sharing for downloads: Read, Write, Delete- When using a mount point of type Another SFTP server, and the other server uses SFTP v3, the SSH Server now lets an SFTP v4+ client set a file modification time without having to also include the last access time.
- The SSH Server now logs most SFTP flags and bits as human-readable strings instead of hexadecimal values.
- FTPS:
- The SSH Server would replace non-US-ASCII bytes with "." when sending reply lines on the FTP control connection. To improve compatibility with clients, the SSH Server now preserves UTF-8 (which may appear in directory names) in FTP control connection replies.
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