FreeBSD Security Advisory (FreeBSD-SA-02:20.syncache.asc)

# SPDX-FileCopyrightText: 2008 E-Soft Inc.
# Some text descriptions might be excerpted from (a) referenced
# source(s), and are Copyright (C) by the respective right holder(s).
#
# SPDX-License-Identifier: GPL-2.0-only

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.52634");
  script_version("2023-07-26T05:05:09+0000");
  script_cve_id("CVE-2002-0518");
  script_tag(name:"last_modification", value:"2023-07-26 05:05:09 +0000 (Wed, 26 Jul 2023)");
  script_tag(name:"creation_date", value:"2008-09-04 20:41:11 +0200 (Thu, 04 Sep 2008)");
  script_tag(name:"cvss_base", value:"5.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:N/I:N/A:P");
  script_name("FreeBSD Security Advisory (FreeBSD-SA-02:20.syncache.asc)");
  script_category(ACT_GATHER_INFO);
  script_copyright("Copyright (C) 2008 E-Soft Inc.");
  script_family("FreeBSD Local Security Checks");
  script_dependencies("gather-package-list.nasl");
  script_mandatory_keys("ssh/login/freebsd", "ssh/login/freebsdpatchlevel");

  script_tag(name:"insight", value:"The SYN cache (syncache) and SYN cookie mechanism (syncookie) are
features of the TCP/IP stack intended to improve resistance to a class
of denial of service attacks known as SYN floods.

Two related problems with syncache were triggered when syncookies were
implemented.

1) When a SYN was accepted via a syncookie, it used an uninitialized
pointer to find the TCP options for the new socket.  This pointer may
be a null pointer, which will cause the machine to crash.

2) A syncache entry is created when a SYN arrives on a listen socket.
If the application which created the listen socket was killed and
restarted --- and therefore recreated the listen socket with a
different inpcb --- an ACK (or duplicate SYN) which later arrived and
matched the existing syncache entry would cause a reference to the old
inpcb pointer.  Depending on the pointer's contents, this might result
in a system crash.

Because syncache/syncookies support was added prior to the release of
FreeBSD 4.5-RELEASE, no other releases are affected.");

  script_tag(name:"solution", value:"Upgrade your system to the appropriate stable release
  or security branch dated after the correction date.");

  script_xref(name:"URL", value:"https://secure1.securityspace.com/smysecure/catid.html?in=FreeBSD-SA-02:20.syncache.asc");

  script_tag(name:"summary", value:"The remote host is missing an update to the system
  as announced in the referenced advisory FreeBSD-SA-02:20.syncache.asc");

  script_tag(name:"qod_type", value:"package");
  script_tag(name:"solution_type", value:"VendorFix");

  exit(0);
}

include("pkg-lib-bsd.inc");

vuln = FALSE;

if(patchlevelcmp(rel:"4.5", patchlevel:"1")<0) {
  vuln = TRUE;
}

if(vuln) {
  security_message(port:0);
} else if (__pkg_match) {
  exit(99);
}