diff -up openssh-8.7p1/pathnames.h.kill-scp openssh-8.7p1/pathnames.h

--- openssh-8.7p1/pathnames.h.kill-scp	2021-09-16 11:37:57.240171687 +0200

+++ openssh-8.7p1/pathnames.h	2021-09-16 11:42:29.183427917 +0200

@@ -42,6 +42,7 @@

 #define _PATH_HOST_XMSS_KEY_FILE	SSHDIR "/ssh_host_xmss_key"

 #define _PATH_HOST_RSA_KEY_FILE		SSHDIR "/ssh_host_rsa_key"

 #define _PATH_DH_MODULI			SSHDIR "/moduli"

+#define _PATH_SCP_KILL_SWITCH		SSHDIR "/disable_scp"

 #ifndef _PATH_SSH_PROGRAM

 #define _PATH_SSH_PROGRAM		"/usr/bin/ssh"

diff -up openssh-8.7p1/scp.1.kill-scp openssh-8.7p1/scp.1

--- openssh-8.7p1/scp.1.kill-scp	2021-09-16 12:09:02.646714578 +0200

+++ openssh-8.7p1/scp.1	2021-09-16 12:26:49.978628226 +0200

@@ -278,6 +278,13 @@ to print debugging messages about their

 By default a 32KB buffer is used.

 .El

 .El

+.Pp

+Usage of SCP protocol can be blocked by creating a world-readable

+.Ar /etc/ssh/disable_scp

+file. If this file exists, when SCP protocol is in use (either remotely or 

+via the

+.Fl O

+option), the program will exit.

 .Sh EXIT STATUS

 .Ex -std scp

 .Sh SEE ALSO

diff -up openssh-8.7p1/scp.c.kill-scp openssh-8.7p1/scp.c

--- openssh-8.7p1/scp.c.kill-scp	2021-09-16 11:42:56.013650519 +0200

+++ openssh-8.7p1/scp.c	2021-09-16 11:53:03.249713836 +0200

@@ -596,6 +596,14 @@ main(int argc, char **argv)

 	if (iamremote)

 		mode = MODE_SCP;

+	if (mode == MODE_SCP) {

+		FILE *f = fopen(_PATH_SCP_KILL_SWITCH, "r");

+		if (f != NULL) {

+			fclose(f);

+			fatal("SCP protocol is forbidden via %s", _PATH_SCP_KILL_SWITCH);

+		}

+	}

+

 	if ((pwd = getpwuid(userid = getuid())) == NULL)

 		fatal("unknown user %u", (u_int) userid);