According to its banner, the remote host appears to be running OpenSSH-portable version 3.6.1 or older.
There is a flaw in such version that could allow an attacker to bypass the access controls set by the administrator of this server.
OpenSSH features a mechanism that can restrict the list of hosts a given user can log from by specifying a pattern in the user key file (ie: *.mynetwork.com would let a user connect only from the local network).
However there is a flaw in the way OpenSSH does reverse DNS lookups.
If an attacker configures a DNS server to send a numeric IP address when a reverse lookup is performed, this mechanism could be circumvented.
#
# (C) Tenable Network Security, Inc.
#
include("compat.inc");
if (description)
{
script_id(11712);
script_version ("1.22");
script_cvs_date("Date: 2018/07/16 14:09:13");
script_cve_id("CVE-2003-0386");
script_bugtraq_id(7831);
script_xref(name:"CERT", value:"978316");
script_name(english:"OpenSSH < 3.6.2 Reverse DNS Lookup Bypass");
script_summary(english:"Checks for the remote SSH version");
script_set_attribute(attribute:"synopsis", value:
"The remote host has an application that is affected by DNS
lookup bypass vulnerability." );
script_set_attribute(attribute:"description", value:
"According to its banner, the remote host appears to be running
OpenSSH-portable version 3.6.1 or older.
There is a flaw in such version that could allow an attacker to
bypass the access controls set by the administrator of this server.
OpenSSH features a mechanism that can restrict the list of
hosts a given user can log from by specifying a pattern
in the user key file (ie: *.mynetwork.com would let a user
connect only from the local network).
However there is a flaw in the way OpenSSH does reverse DNS lookups.
If an attacker configures a DNS server to send a numeric IP address
when a reverse lookup is performed, this mechanism could be
circumvented." );
script_set_attribute(attribute:"solution", value:
"Upgrade to OpenSSH 3.6.2 or later." );
script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
script_set_attribute(attribute:"exploit_available", value:"false");
script_set_attribute(attribute:"plugin_publication_date", value: "2003/06/10");
script_set_attribute(attribute:"vuln_publication_date", value: "2003/06/05");
script_set_attribute(attribute:"plugin_type", value: "remote");
script_set_attribute(attribute:"cpe", value:"cpe:/a:openbsd:openssh");
script_end_attributes();
script_category(ACT_GATHER_INFO);
script_copyright(english:"This script is Copyright (C) 2003-2018 Tenable Network Security, Inc.");
script_family(english:"Misc.");
script_dependencie("ssh_detect.nasl");
script_require_ports("Services/ssh", 22);
exit(0);
}
include("backport.inc");
include("global_settings.inc");
include("misc_func.inc");
# Ensure the port is open.
port = get_service(svc:"ssh", exit_on_fail:TRUE);
# Get banner for service.
banner = get_kb_item_or_exit("SSH/banner/"+port);
bp_banner = tolower(get_backport_banner(banner:banner));
if ("openssh" >!< bp_banner) exit(0, "The SSH service on port "+port+" is not OpenSSH.");
if (backported) exit(1, "The banner from the OpenSSH server on port "+port+" indicates patches may have been backported.");
if (ereg(pattern:"openssh[-_]((1\..*)|(2\..*)|(3\.([0-5][^0-9]|6(\.[01])?$)))", string:bp_banner))
security_hole(port);