Vulnerabilities > CVE-2008-4109 - Unspecified vulnerability in Openbsd Openssh

047910
CVSS 0.0 - NONE
Attack vector
UNKNOWN
Attack complexity
UNKNOWN
Privileges required
UNKNOWN
Confidentiality impact
UNKNOWN
Integrity impact
UNKNOWN
Availability impact
UNKNOWN
openbsd
nessus

Summary

A certain Debian patch for OpenSSH before 4.3p2-9etch3 on etch; before 4.6p1-1 on sid and lenny; and on other distributions such as SUSE uses functions that are not async-signal-safe in the signal handler for login timeouts, which allows remote attackers to cause a denial of service (connection slot exhaustion) via multiple login attempts. NOTE: this issue exists because of an incorrect fix for CVE-2006-5051.

Vulnerable Configurations

Part Description Count
Application
Debian
2
Application
Openbsd
143

Nessus

  • NASL familyMisc.
    NASL idOPENSSH_44.NASL
    descriptionAccording to its banner, the version of OpenSSH installed on the remote host is affected by multiple vulnerabilities : - A race condition exists that may allow an unauthenticated, remote attacker to crash the service or, on portable OpenSSH, possibly execute code on the affected host. Note that successful exploitation requires that GSSAPI authentication be enabled. - A flaw exists that may allow an attacker to determine the validity of usernames on some platforms. Note that this issue requires that GSSAPI authentication be enabled. - When SSH version 1 is used, an issue can be triggered via an SSH packet that contains duplicate blocks that could result in a loss of availability for the service. - On Fedora Core 6 (and possibly other systems), an unspecified vulnerability in the linux_audit_record_event() function allows remote attackers to inject incorrect information into audit logs.
    last seen2020-06-01
    modified2020-06-02
    plugin id22466
    published2006-09-28
    reporterThis script is Copyright (C) 2006-2018 Tenable Network Security, Inc.
    sourcehttps://www.tenable.com/plugins/nessus/22466
    titleOpenSSH < 4.4 Multiple Vulnerabilities
    code
    #
    # (C) Tenable Network Security, Inc.
    #
    
    include("compat.inc");
    
    if (description) 
    {
      script_id(22466);
      script_version("1.30");
      script_cvs_date("Date: 2018/07/16 14:09:13");
    
      script_cve_id("CVE-2006-4924", "CVE-2006-4925", "CVE-2006-5051", "CVE-2006-5052", "CVE-2006-5229", "CVE-2007-3102", "CVE-2008-4109");
      script_bugtraq_id(20216, 20241, 20245);
    
      script_name(english:"OpenSSH < 4.4 Multiple Vulnerabilities");
      script_summary(english:"Checks version number of OpenSSH");
     
      script_set_attribute(attribute:"synopsis", value:
    "The remote SSH server is affected by multiple vulnerabilities." );
      script_set_attribute(attribute:"description", value:
    "According to its banner, the version of OpenSSH installed on the
    remote host is affected by multiple vulnerabilities :
    
      - A race condition exists that may allow an
        unauthenticated, remote attacker to crash the service 
        or, on portable OpenSSH, possibly execute code on the 
        affected host.  Note that successful exploitation 
        requires that GSSAPI authentication be enabled.
        
      - A flaw exists that may allow an attacker to determine 
        the validity of usernames on some platforms. Note that 
        this issue requires that GSSAPI authentication be 
        enabled.
    
      - When SSH version 1 is used, an issue can be triggered 
        via an SSH packet that contains duplicate blocks that 
        could result in a loss of availability for the service.
    
      - On Fedora Core 6 (and possibly other systems), an
        unspecified vulnerability in the
        linux_audit_record_event() function allows remote
        attackers to inject incorrect information into
        audit logs.");
    
      script_set_attribute(attribute:"see_also", value:"http://www.openssh.com/txt/release-4.4" );
      script_set_attribute(attribute:"solution", value:
    "Upgrade to OpenSSH 4.4 or later." );
      script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:C/I:C/A:C");
      script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
      script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
      script_set_attribute(attribute:"exploit_available", value:"true");
      script_cwe_id(264, 362, 399);
      script_set_attribute(attribute:"plugin_publication_date", value: "2006/09/28");
      script_set_attribute(attribute:"vuln_publication_date", value: "2006/09/28");
      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_family(english:"Misc.");
      script_copyright(english:"This script is Copyright (C) 2006-2018 Tenable Network Security, Inc.");
      script_dependencies("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 (!get_kb_item("Settings/PCI_DSS"))
    {
      auth = get_kb_item_or_exit("SSH/supportedauth/" + port);
      if ("gssapi" >!< auth) exit(0, "The SSH service on port "+port+" doesn't support GSSAPI.");
    }
    
    if (bp_banner =~ "openssh[-_]([0-3]\.|4\.[0-3]([^0-9]|$))")
      security_hole(port);
    
  • NASL familyDebian Local Security Checks
    NASL idDEBIAN_DSA-1638.NASL
    descriptionIt has been discovered that the signal handler implementing the login timeout in Debian
    last seen2020-06-01
    modified2020-06-02
    plugin id34223
    published2008-09-17
    reporterThis script is Copyright (C) 2008-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/34223
    titleDebian DSA-1638-1 : openssh - denial of service
    code
    #%NASL_MIN_LEVEL 80502
    #
    # (C) Tenable Network Security, Inc.
    #
    # The descriptive text and package checks in this plugin were  
    # extracted from Debian Security Advisory DSA-1638. The text 
    # itself is copyright (C) Software in the Public Interest, Inc.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(34223);
      script_version("1.17");
      script_cvs_date("Date: 2019/08/02 13:32:21");
    
      script_cve_id("CVE-2006-5051", "CVE-2008-4109");
      script_bugtraq_id(20241);
      script_xref(name:"DSA", value:"1638");
    
      script_name(english:"Debian DSA-1638-1 : openssh - denial of service");
      script_summary(english:"Checks dpkg output for the updated package");
    
      script_set_attribute(
        attribute:"synopsis", 
        value:"The remote Debian host is missing a security-related update."
      );
      script_set_attribute(
        attribute:"description", 
        value:
    "It has been discovered that the signal handler implementing the login
    timeout in Debian's version of the OpenSSH server uses functions which
    are not async-signal-safe, leading to a denial of service
    vulnerability (CVE-2008-4109 ).
    
    The problem was originally corrected in OpenSSH 4.4p1 (CVE-2006-5051
    ), but the patch backported to the version released with etch was
    incorrect.
    
    Systems affected by this issue suffer from lots of zombie sshd
    processes. Processes stuck with a '[net]' process title have also been
    observed. Over time, a sufficient number of processes may accumulate
    such that further login attempts are impossible. Presence of these
    processes does not indicate active exploitation of this vulnerability.
    It is possible to trigger this denial of service condition by
    accident."
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=498678"
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://security-tracker.debian.org/tracker/CVE-2008-4109"
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://security-tracker.debian.org/tracker/CVE-2006-5051"
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://www.debian.org/security/2008/dsa-1638"
      );
      script_set_attribute(
        attribute:"solution", 
        value:
    "Upgrade the openssh packages.
    
    For the stable distribution (etch), this problem has been fixed in
    version 4.3p2-9etch3."
      );
      script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:C/I:C/A:C");
      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_cwe_id(264, 362);
    
      script_set_attribute(attribute:"plugin_type", value:"local");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:openssh");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:4.0");
    
      script_set_attribute(attribute:"patch_publication_date", value:"2008/09/16");
      script_set_attribute(attribute:"plugin_publication_date", value:"2008/09/17");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_copyright(english:"This script is Copyright (C) 2008-2019 and is owned by Tenable, Inc. or an Affiliate thereof.");
      script_family(english:"Debian Local Security Checks");
    
      script_dependencies("ssh_get_info.nasl");
      script_require_keys("Host/local_checks_enabled", "Host/Debian/release", "Host/Debian/dpkg-l");
    
      exit(0);
    }
    
    
    include("audit.inc");
    include("debian_package.inc");
    
    
    if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
    if (!get_kb_item("Host/Debian/release")) audit(AUDIT_OS_NOT, "Debian");
    if (!get_kb_item("Host/Debian/dpkg-l")) audit(AUDIT_PACKAGE_LIST_MISSING);
    
    
    flag = 0;
    if (deb_check(release:"4.0", prefix:"openssh-client", reference:"4.3p2-9etch3")) flag++;
    if (deb_check(release:"4.0", prefix:"openssh-server", reference:"4.3p2-9etch3")) flag++;
    if (deb_check(release:"4.0", prefix:"ssh", reference:"4.3p2-9etch3")) flag++;
    if (deb_check(release:"4.0", prefix:"ssh-askpass-gnome", reference:"4.3p2-9etch3")) flag++;
    if (deb_check(release:"4.0", prefix:"ssh-krb5", reference:"4.3p2-9etch3")) flag++;
    
    if (flag)
    {
      if (report_verbosity > 0) security_hole(port:0, extra:deb_report_get());
      else security_hole(0);
      exit(0);
    }
    else audit(AUDIT_HOST_NOT, "affected");
    
  • NASL familySuSE Local Security Checks
    NASL idSUSE_OPENSSH-5627.NASL
    descriptionDue to a faulty signal handler repeated login attempts could exhaust the maximum allowed connections and prevent further logins. (CVE-2008-4109) A problem where utmp entries where not deleted when users logged out was also fixed.
    last seen2020-06-01
    modified2020-06-02
    plugin id34321
    published2008-10-01
    reporterThis script is Copyright (C) 2008-2019 Tenable Network Security, Inc.
    sourcehttps://www.tenable.com/plugins/nessus/34321
    titleSuSE 10 Security Update : OpenSSH (ZYPP Patch Number 5627)
    code
    #%NASL_MIN_LEVEL 80502
    #
    # (C) Tenable Network Security, Inc.
    #
    # The text description of this plugin is (C) Novell, Inc.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(34321);
      script_version ("1.17");
      script_cvs_date("Date: 2019/10/25 13:36:33");
    
      script_cve_id("CVE-2008-4109");
    
      script_name(english:"SuSE 10 Security Update : OpenSSH (ZYPP Patch Number 5627)");
      script_summary(english:"Checks rpm output for the updated packages");
    
      script_set_attribute(
        attribute:"synopsis", 
        value:"The remote SuSE 10 host is missing a security-related patch."
      );
      script_set_attribute(
        attribute:"description", 
        value:
    "Due to a faulty signal handler repeated login attempts could exhaust
    the maximum allowed connections and prevent further logins.
    (CVE-2008-4109)
    
    A problem where utmp entries where not deleted when users logged out
    was also fixed."
      );
      script_set_attribute(
        attribute:"see_also",
        value:"http://support.novell.com/security/cve/CVE-2008-4109.html"
      );
      script_set_attribute(attribute:"solution", value:"Apply ZYPP patch number 5627.");
      script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P");
      script_cwe_id(264);
    
      script_set_attribute(attribute:"plugin_type", value:"local");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:suse:suse_linux");
    
      script_set_attribute(attribute:"patch_publication_date", value:"2008/09/23");
      script_set_attribute(attribute:"plugin_publication_date", value:"2008/10/01");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_copyright(english:"This script is Copyright (C) 2008-2019 Tenable Network Security, Inc.");
      script_family(english:"SuSE Local Security Checks");
    
      script_dependencies("ssh_get_info.nasl");
      script_require_keys("Host/local_checks_enabled", "Host/cpu", "Host/SuSE/release", "Host/SuSE/rpm-list");
    
      exit(0);
    }
    
    
    include("global_settings.inc");
    include("rpm.inc");
    
    
    if (!get_kb_item("Host/local_checks_enabled")) exit(0, "Local checks are not enabled.");
    if (!get_kb_item("Host/SuSE/release")) exit(0, "The host is not running SuSE.");
    if (!get_kb_item("Host/SuSE/rpm-list")) exit(1, "Could not obtain the list of installed packages.");
    
    cpu = get_kb_item("Host/cpu");
    if (isnull(cpu)) exit(1, "Failed to determine the architecture type.");
    if (cpu >!< "x86_64" && cpu !~ "^i[3-6]86$") exit(1, "Local checks for SuSE 10 on the '"+cpu+"' architecture have not been implemented.");
    
    
    flag = 0;
    if (rpm_check(release:"SLED10", sp:1, reference:"openssh-4.2p1-18.38.3")) flag++;
    if (rpm_check(release:"SLED10", sp:1, reference:"openssh-askpass-4.2p1-18.38.3")) flag++;
    if (rpm_check(release:"SLED10", sp:2, reference:"openssh-4.2p1-18.38.3")) flag++;
    if (rpm_check(release:"SLED10", sp:2, reference:"openssh-askpass-4.2p1-18.38.3")) flag++;
    if (rpm_check(release:"SLES10", sp:1, reference:"openssh-4.2p1-18.38.3")) flag++;
    if (rpm_check(release:"SLES10", sp:1, reference:"openssh-askpass-4.2p1-18.38.3")) flag++;
    if (rpm_check(release:"SLES10", sp:2, reference:"openssh-4.2p1-18.38.3")) flag++;
    if (rpm_check(release:"SLES10", sp:2, reference:"openssh-askpass-4.2p1-18.38.3")) flag++;
    
    
    if (flag)
    {
      if (report_verbosity > 0) security_warning(port:0, extra:rpm_report_get());
      else security_warning(0);
      exit(0);
    }
    else exit(0, "The host is not affected.");
    
  • NASL familyMandriva Local Security Checks
    NASL idMANDRAKE_MDKSA-2006-179.NASL
    descriptionTavis Ormandy of the Google Security Team discovered a Denial of Service vulnerability in the SSH protocol version 1 CRC compensation attack detector. This could allow a remote unauthenticated attacker to trigger excessive CPU utilization by sending a specially crafted SSH message, which would then deny ssh services to other users or processes (CVE-2006-4924, CVE-2006-4925). Please note that Mandriva ships with only SSH protocol version 2 enabled by default. Next, an unsafe signal handler was found by Mark Dowd. This signal handler was vulnerable to a race condition that could be exploited to perform a pre-authentication DoS, and theoretically a pre-authentication remote code execution in the case where some authentication methods like GSSAPI are enabled (CVE-2006-5051). Updated packages have been patched to correct this issue.
    last seen2020-06-01
    modified2020-06-02
    plugin id24565
    published2007-02-18
    reporterThis script is Copyright (C) 2007-2019 Tenable Network Security, Inc.
    sourcehttps://www.tenable.com/plugins/nessus/24565
    titleMandrake Linux Security Advisory : openssh (MDKSA-2006:179)
  • NASL familyUbuntu Local Security Checks
    NASL idUBUNTU_USN-355-1.NASL
    descriptionTavis Ormandy discovered that the SSH daemon did not properly handle authentication packets with duplicated blocks. By sending specially crafted packets, a remote attacker could exploit this to cause the ssh daemon to drain all available CPU resources until the login grace time expired. (CVE-2006-4924) Mark Dowd discovered a race condition in the server
    last seen2020-06-01
    modified2020-06-02
    plugin id27935
    published2007-11-10
    reporterUbuntu Security Notice (C) 2007-2019 Canonical, Inc. / NASL script (C) 2018 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/27935
    titleUbuntu 5.04 / 5.10 / 6.06 LTS : openssh vulnerabilities (USN-355-1)
  • NASL familyMisc.
    NASL idSUNSSH_PLAINTEXT_RECOVERY.NASL
    descriptionThe version of SunSSH running on the remote host has an information disclosure vulnerability. A design flaw in the SSH specification could allow a man-in-the-middle attacker to recover up to 32 bits of plaintext from an SSH-protected connection in the standard configuration. An attacker could exploit this to gain access to sensitive information. Note that this version of SunSSH is also prone to several additional issues but Nessus did not test for them.
    last seen2020-06-01
    modified2020-06-02
    plugin id55992
    published2011-08-29
    reporterThis script is Copyright (C) 2011-2018 Tenable Network Security, Inc.
    sourcehttps://www.tenable.com/plugins/nessus/55992
    titleSunSSH < 1.1.1 / 1.3 CBC Plaintext Disclosure
  • NASL familySuSE Local Security Checks
    NASL idSUSE9_12257.NASL
    descriptionDue to a faulty signal handler repeated login attempts could exhaust the maximum allowed connections and prevent further logins. (CVE-2008-4109)
    last seen2020-06-01
    modified2020-06-02
    plugin id41244
    published2009-09-24
    reporterThis script is Copyright (C) 2009-2019 Tenable Network Security, Inc.
    sourcehttps://www.tenable.com/plugins/nessus/41244
    titleSuSE9 Security Update : OpenSSH (YOU Patch Number 12257)
  • NASL familyUbuntu Local Security Checks
    NASL idUBUNTU_USN-649-1.NASL
    descriptionIt was discovered that the ForceCommand directive could be bypassed. If a local user created a malicious ~/.ssh/rc file, they could execute arbitrary commands as their user id. This only affected Ubuntu 7.10. (CVE-2008-1657) USN-355-1 fixed vulnerabilities in OpenSSH. It was discovered that the fixes for this issue were incomplete. A remote attacker could attempt multiple logins, filling all available connection slots, leading to a denial of service. This only affected Ubuntu 6.06 and 7.04. (CVE-2008-4109). Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen2020-06-01
    modified2020-06-02
    plugin id36855
    published2009-04-23
    reporterUbuntu Security Notice (C) 2009-2019 Canonical, Inc. / NASL script (C) 2018 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/36855
    titleUbuntu 6.06 LTS / 7.04 / 7.10 : openssh vulnerabilities (USN-649-1)

Statements

contributorJoshua Bressers
lastmodified2017-08-07
organizationRed Hat
statementNot vulnerable. The patch used to fix CVE-2006-5051 in Red Hat Enterprise Linux 2.1, 3, 4, and 5 was complete and does not suffer from this problem.