Thanks for your reply. Just to make sure, I added a new connection, exported it to a script which looks like this:
open sftp://XXXXXX@XXXXXX/ -hostkey="ssh-rsa 2048 8e:85:93:e0:19:61:7a:0c:05:4a:b4:58:54:05:06:58" -rawsettings TryAgent=0 GSSAPIFwdTGT=1 GSSCustom="C:%5CProgram%20Files%20(x86)%5CHeimdal%5Cbin%5Cgssapi.dll"
exit
. 2017-11-23 14:51:30.014 --------------------------------------------------------------------------
. 2017-11-23 14:51:30.014 WinSCP Version 5.11.2 (Build 7781) (OS 6.1.7601 Service Pack 1 - Windows 7 Enterprise)
. 2017-11-23 14:51:30.014 Configuration: nul
. 2017-11-23 14:51:30.015 Log level: Normal
[...]
. 2017-11-23 14:51:30.015 Command-line: "C:\Program Files (x86)\WinSCP\WinSCP.exe" /log="C:\Users\XXXXXX\Desktop\WinSCP.log" /ini=nul /script="C:\Users\XXXXXX\Desktop\winscp.txt"
. 2017-11-23 14:51:30.015 Time zone: Current: GMT+1, Standard: GMT+1 (W. Europe Standard Time), DST: GMT+2 (W. Europe Daylight Time), DST Start: 26.03.2017, DST End: 29.10.2017
. 2017-11-23 14:51:30.015 Login time: Donnerstag, 23. November 2017 14:51:30
. 2017-11-23 14:51:30.015 --------------------------------------------------------------------------
. 2017-11-23 14:51:30.015 Script: Retrospectively logging previous script records:
> 2017-11-23 14:51:30.015 Script: open sftp://XXXXXX@XXXXXX/ -hostkey="ssh-rsa 2048 8e:85:93:e0:19:61:7a:0c:05:4a:b4:58:54:05:06:58" -rawsettings TryAgent=0 GSSAPIFwdTGT=1 GSSCustom="C:%5CProgram%20Files%20(x86)%5CHeimdal%5Cbin%5Cgssapi.dll"
. 2017-11-23 14:51:30.015 --------------------------------------------------------------------------
. 2017-11-23 14:51:30.015 Session name: XXXXXX@XXXXXX (Ad-Hoc site)
. 2017-11-23 14:51:30.015 Host name: XXXXXX (Port: 22)
. 2017-11-23 14:51:30.015 User name: XXXXXX (Password: No, Key file: No, Passphrase: No)
. 2017-11-23 14:51:30.015 Tunnel: No
. 2017-11-23 14:51:30.015 Transfer Protocol: SFTP
. 2017-11-23 14:51:30.015 Ping type: Off, Ping interval: 30 sec; Timeout: 15 sec
. 2017-11-23 14:51:30.015 Disable Nagle: No
. 2017-11-23 14:51:30.015 Proxy: None
. 2017-11-23 14:51:30.015 Send buffer: 262144
. 2017-11-23 14:51:30.015 SSH protocol version: 2; Compression: No
. 2017-11-23 14:51:30.015 Bypass authentication: No
. 2017-11-23 14:51:30.015 Try agent: No; Agent forwarding: No; TIS/CryptoCard: No; KI: Yes; GSSAPI: Yes
. 2017-11-23 14:51:30.015 GSSAPI: Forwarding: Yes
. 2017-11-23 14:51:30.016 Ciphers: aes,chacha20,blowfish,3des,WARN,arcfour,des; Ssh2DES: No
. 2017-11-23 14:51:30.016 KEX: ecdh,dh-gex-sha1,dh-group14-sha1,rsa,WARN,dh-group1-sha1
. 2017-11-23 14:51:30.016 SSH Bugs: Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto
. 2017-11-23 14:51:30.016 Simple channel: Yes
. 2017-11-23 14:51:30.016 Return code variable: Autodetect; Lookup user groups: Auto
. 2017-11-23 14:51:30.016 Shell: default
. 2017-11-23 14:51:30.016 EOL: LF, UTF: Auto
. 2017-11-23 14:51:30.016 Clear aliases: Yes, Unset nat.vars: Yes, Resolve symlinks: Yes; Follow directory symlinks: No
. 2017-11-23 14:51:30.016 LS: ls -la, Ign LS warn: Yes, Scp1 Comp: No
. 2017-11-23 14:51:30.016 SFTP Bugs: Auto,Auto
. 2017-11-23 14:51:30.016 SFTP Server: default
. 2017-11-23 14:51:30.016 Local directory: default, Remote directory: home, Update: Yes, Cache: Yes
. 2017-11-23 14:51:30.016 Cache directory changes: Yes, Permanent: Yes
. 2017-11-23 14:51:30.016 Recycle bin: Delete to: No, Overwritten to: No, Bin path:
. 2017-11-23 14:51:30.016 DST mode: Unix
. 2017-11-23 14:51:30.016 --------------------------------------------------------------------------
. 2017-11-23 14:51:30.016 Looking up host "XXXXXX" for SSH connection
. 2017-11-23 14:51:30.026 Connecting to 130.75.103.223 port 22
. 2017-11-23 14:51:30.029 We claim version: SSH-2.0-WinSCP_release_5.11.2
. 2017-11-23 14:51:30.049 Server version: SSH-2.0-OpenSSH_7.4p1 Debian-10+deb9u1
. 2017-11-23 14:51:30.049 Using SSH protocol version 2
. 2017-11-23 14:51:30.050 Have a known host key of type rsa2
. 2017-11-23 14:51:30.054 Doing ECDH key exchange with curve Curve25519 and hash SHA-256
. 2017-11-23 14:51:30.179 Server also has ssh-ed25519/ecdsa-sha2-nistp256 host keys, but we don't know any of them
. 2017-11-23 14:51:30.179 Host key fingerprint is:
. 2017-11-23 14:51:30.179 ssh-rsa 2048 8e:85:93:e0:19:61:7a:0c:05:4a:b4:58:54:05:06:58
. 2017-11-23 14:51:30.179 Verifying host key rsa2 0x23,0xa42a961ac636acff cc124e739131d082 7f2f37cd8585630f d352291543367e49 6480d8cd387d93bb feafdc0552373dc4 f77fdb12a095edf0 f64c19dc0303bcee fecce0d09b939c8d 5629efd996c2ed1a afef0ebe25817c20 e6230d31cd6cf97f a4664edc093842e5 fa77ddf4b5cdf21f eb3716147947dbf5 a51a894d56f205d4 feda8ea2185a211e 6287a3cf7487500f 665a4ca13824fab5 d90c285a25238b85 de8ff1356f658c2d e1531a0165ff1789 b298f0f1a4c7f5c2 7146d22a6dd1c4fe 2abd0f07a20c04d4 0ec3c9f0de22a59a 46a01d819fc38cf1 ce47060e3c25d6e1 6c78ddbc8dd41d80 0819f8a87befd4d4 5b4b265f6ac061fd 91e0c282e14d9c87 with fingerprint ssh-rsa 2048 8e:85:93:e0:19:61:7a:0c:05:4a:b4:58:54:05:06:58
. 2017-11-23 14:51:30.179 Host key matches configured key
. 2017-11-23 14:51:30.179 Initialised AES-256 SDCTR client->server encryption
. 2017-11-23 14:51:30.179 Initialised HMAC-SHA-256 client->server MAC algorithm
. 2017-11-23 14:51:30.179 Initialised AES-256 SDCTR server->client encryption
. 2017-11-23 14:51:30.179 Initialised HMAC-SHA-256 server->client MAC algorithm
! 2017-11-23 14:51:30.226 Using username "XXXXXX".
. 2017-11-23 14:51:30.232 Server offered these authentication methods: publickey,gssapi-keyex,gssapi-with-mic,password
. 2017-11-23 14:51:31.198 Using SSPI from SECUR32.DLL
. 2017-11-23 14:51:31.198 Attempting GSSAPI authentication
. 2017-11-23 14:51:31.204 GSSAPI authentication initialisation failed
. 2017-11-23 14:51:31.204 No credentials are available in the security package.
. 2017-11-23 14:51:31.204 Prompt (password, "SSH password", <no instructions>, "&Password: ")
. 2017-11-23 14:51:31.205 Disconnected: Unable to authenticate