RHSA-2002:287

Vulnerability from csaf_redhat - Published: 2003-01-16 15:46 - Updated: 2025-11-21 17:25
Summary
Red Hat Security Advisory: vnc security update

Notes

Topic
Updated VNC packages are available to fix a challenge replay attack that is present in the VNC server.
Details
VNC is a tool for providing a remote graphical user interface. The VNC DES authentication scheme is implemented using a challenge-response architecture, producing a random and different challenge for each authentication attempt. A bug in the function for generating the random challenge caused the random seed to be reset to the current time on every authentication attempt. As a result, two authentication attempts within the same second could receive the same challenge. An eavesdropper could exploit this vulnerability by replaying the response, thereby gaining authentication. All users of VNC are advised to upgrade to these errata packages, which contain an updated version and are not vulnerable to this issue. Note that when using VNC on an untrusted network, always make sure to tunnel the VNC protocol through a secure, authenticated channel such as SSH. Instructions on how to tunnel VNC through SSH are provided at the following URL: http://www.uk.research.att.com/vnc/sshvnc.html
Terms of Use
This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original.
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{
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      "text": "Moderate"
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    "category": "csaf_security_advisory",
    "csaf_version": "2.0",
    "distribution": {
      "text": "Copyright \u00a9 Red Hat, Inc. All rights reserved.",
      "tlp": {
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    "lang": "en",
    "notes": [
      {
        "category": "summary",
        "text": "Updated VNC packages are available to fix a challenge replay attack that is\npresent in the VNC server.",
        "title": "Topic"
      },
      {
        "category": "general",
        "text": "VNC is a tool for providing a remote graphical user interface.\n\nThe VNC DES authentication scheme is implemented using a challenge-response\narchitecture, producing a random and different challenge for each\nauthentication attempt.\n\nA bug in the function for generating the random challenge caused the random\nseed to be reset to the current time on every authentication attempt.\nAs a result, two authentication attempts within the same second could\nreceive the same challenge. An eavesdropper could exploit this\nvulnerability by replaying the response, thereby gaining authentication.\n\nAll users of VNC are advised to upgrade to these errata packages, which\ncontain an updated version and are not vulnerable to this issue. \n\nNote that when using VNC on an untrusted network, always make sure to\ntunnel the VNC protocol through a secure, authenticated channel such as\nSSH.  Instructions on how to tunnel VNC through SSH are provided at the\nfollowing URL: http://www.uk.research.att.com/vnc/sshvnc.html",
        "title": "Details"
      },
      {
        "category": "legal_disclaimer",
        "text": "This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original.",
        "title": "Terms of Use"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "https://access.redhat.com/security/team/contact/",
      "issuing_authority": "Red Hat Product Security is responsible for vulnerability handling across all Red Hat products and services.",
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      "namespace": "https://www.redhat.com"
    },
    "references": [
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        "category": "self",
        "summary": "https://access.redhat.com/errata/RHSA-2002:287",
        "url": "https://access.redhat.com/errata/RHSA-2002:287"
      },
      {
        "category": "external",
        "summary": "https://access.redhat.com/security/updates/classification/#moderate",
        "url": "https://access.redhat.com/security/updates/classification/#moderate"
      },
      {
        "category": "external",
        "summary": "http://marc.theaimsgroup.com/?l=bugtraq\u0026m=102753170201524",
        "url": "http://marc.theaimsgroup.com/?l=bugtraq\u0026m=102753170201524"
      },
      {
        "category": "external",
        "summary": "78828",
        "url": "https://bugzilla.redhat.com/show_bug.cgi?id=78828"
      },
      {
        "category": "self",
        "summary": "Canonical URL",
        "url": "https://security.access.redhat.com/data/csaf/v2/advisories/2003/rhsa-2002_287.json"
      }
    ],
    "title": "Red Hat Security Advisory: vnc security update",
    "tracking": {
      "current_release_date": "2025-11-21T17:25:15+00:00",
      "generator": {
        "date": "2025-11-21T17:25:15+00:00",
        "engine": {
          "name": "Red Hat SDEngine",
          "version": "4.6.12"
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      },
      "id": "RHSA-2002:287",
      "initial_release_date": "2003-01-16T15:46:00+00:00",
      "revision_history": [
        {
          "date": "2003-01-16T15:46:00+00:00",
          "number": "1",
          "summary": "Initial version"
        },
        {
          "date": "2003-02-07T00:00:00+00:00",
          "number": "2",
          "summary": "Last updated version"
        },
        {
          "date": "2025-11-21T17:25:15+00:00",
          "number": "3",
          "summary": "Last generated version"
        }
      ],
      "status": "final",
      "version": "3"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_name",
                "name": "Red Hat Enterprise Linux AS (Advanced Server) version 2.1 ",
                "product": {
                  "name": "Red Hat Enterprise Linux AS (Advanced Server) version 2.1 ",
                  "product_id": "Red Hat Enterprise Linux AS (Advanced Server) version 2.1 ",
                  "product_identification_helper": {
                    "cpe": "cpe:/o:redhat:enterprise_linux:2.1::as"
                  }
                }
              }
            ],
            "category": "product_family",
            "name": "Red Hat Advanced Server"
          }
        ],
        "category": "vendor",
        "name": "Red Hat"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2002-1336",
      "ids": [
        {
          "system_name": "Red Hat Bugzilla ID",
          "text": "1616876"
        }
      ],
      "notes": [
        {
          "category": "description",
          "text": "TightVNC before 1.2.6 generates the same challenge string for multiple connections, which allows remote attackers to bypass VNC authentication by sniffing the challenge and response of other users.",
          "title": "Vulnerability description"
        },
        {
          "category": "summary",
          "text": "security flaw",
          "title": "Vulnerability summary"
        }
      ],
      "product_status": {
        "fixed": [
          "Red Hat Enterprise Linux AS (Advanced Server) version 2.1 "
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "Canonical URL",
          "url": "https://access.redhat.com/security/cve/CVE-2002-1336"
        },
        {
          "category": "external",
          "summary": "RHBZ#1616876",
          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1616876"
        },
        {
          "category": "external",
          "summary": "https://www.cve.org/CVERecord?id=CVE-2002-1336",
          "url": "https://www.cve.org/CVERecord?id=CVE-2002-1336"
        },
        {
          "category": "external",
          "summary": "https://nvd.nist.gov/vuln/detail/CVE-2002-1336",
          "url": "https://nvd.nist.gov/vuln/detail/CVE-2002-1336"
        }
      ],
      "release_date": "2002-07-26T00:00:00+00:00",
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2003-01-16T15:46:00+00:00",
          "details": "Before applying this update, make sure all previously released errata\nrelevant to your system have been applied.\n\nTo update all RPMs for your particular architecture, run:\n\nrpm -Fvh [filenames]\n\nwhere [filenames] is a list of the RPMs you wish to upgrade.  Only those\nRPMs which are currently installed will be updated.  Those RPMs which are\nnot installed but included in the list will not be updated.  Note that you\ncan also use wildcards (*.rpm) if your current directory *only* contains the\ndesired RPMs.\n\nPlease note that this update is also available via Red Hat Network.  Many\npeople find this an easier way to apply updates.  To use Red Hat Network,\nlaunch the Red Hat Update Agent with the following command:\n\nup2date\n\nThis will start an interactive process that will result in the appropriate\nRPMs being upgraded on your system.",
          "product_ids": [
            "Red Hat Enterprise Linux AS (Advanced Server) version 2.1 "
          ],
          "restart_required": {
            "category": "none"
          },
          "url": "https://access.redhat.com/errata/RHSA-2002:287"
        }
      ],
      "threats": [
        {
          "category": "impact",
          "details": "Moderate"
        }
      ],
      "title": "security flaw"
    }
  ]
}


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Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.