GSD-2018-1000539

Vulnerability from gsd - Updated: 2018-04-30 00:00
Details
Ruby's OpenSSL bindings do not check the length of the supplied authentication tag when decrypting an authenticated encryption mode such as AES-GCM, leaving this up to the authors of a gem/app to implement for properly validating the message. json-jwt was not checking for the authentication tag length, meaning that with a one byte tag the JWT would be considered not tampered with. This means that with an average of 128 (max 256) attempts an attacker can forge a valid signature.
Aliases
Aliases
CVE-2018-1000539
To clipboard 

{
  "GSD": {
    "alias": "CVE-2018-1000539",
    "description": "Nov json-jwt version \u003e= 0.5.0 \u0026\u0026 \u003c 1.9.4 contains a CWE-347: Improper Verification of Cryptographic Signature vulnerability in Decryption of AES-GCM encrypted JSON Web Tokens that can result in Attacker can forge a authentication tag. This attack appear to be exploitable via network connectivity. This vulnerability appears to have been fixed in 1.9.4 and later.",
    "id": "GSD-2018-1000539",
    "references": [
      "https://www.suse.com/security/cve/CVE-2018-1000539.html",
      "https://www.debian.org/security/2018/dsa-4283"
    ]
  },
  "gsd": {
    "metadata": {
      "exploitCode": "unknown",
      "remediation": "unknown",
      "reportConfidence": "confirmed",
      "type": "vulnerability"
    },
    "osvSchema": {
      "affected": [
        {
          "package": {
            "ecosystem": "RubyGems",
            "name": "json-jwt",
            "purl": "pkg:gem/json-jwt"
          }
        }
      ],
      "aliases": [
        "CVE-2018-1000539",
        "GHSA-mj4x-wcxf-hm8x"
      ],
      "details": "Ruby\u0027s OpenSSL bindings do not check the length of the supplied\nauthentication tag when decrypting an authenticated encryption mode\nsuch as AES-GCM, leaving this up to the authors of a gem/app to\nimplement for properly validating the message.\n\njson-jwt was not checking for the authentication tag length, meaning\nthat with a one byte tag the JWT would be considered not tampered\nwith. This means that with an average of 128 (max 256) attempts an\nattacker can forge a valid signature.\n",
      "id": "GSD-2018-1000539",
      "modified": "2018-04-30T00:00:00.000Z",
      "published": "2018-04-30T00:00:00.000Z",
      "references": [
        {
          "type": "WEB",
          "url": "https://github.com/nov/json-jwt/pull/62"
        }
      ],
      "schema_version": "1.4.0",
      "severity": [
        {
          "score": 5.3,
          "type": "CVSS_V3"
        }
      ],
      "summary": "Auth tag forgery vulnerability with AES-GCM encrypted JWT"
    }
  },
  "namespaces": {
    "cve.org": {
      "CVE_data_meta": {
        "ASSIGNER": "cve@mitre.org",
        "DATE_ASSIGNED": "2018-06-23T11:22:33.054763",
        "DATE_REQUESTED": "2018-05-01T19:32:34",
        "ID": "CVE-2018-1000539",
        "REQUESTER": "bartdewater@gmail.com",
        "STATE": "PUBLIC"
      },
      "affects": {
        "vendor": {
          "vendor_data": [
            {
              "product": {
                "product_data": [
                  {
                    "product_name": "n/a",
                    "version": {
                      "version_data": [
                        {
                          "version_value": "n/a"
                        }
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            "value": "Nov json-jwt version \u003e= 0.5.0 \u0026\u0026 \u003c 1.9.4 contains a CWE-347: Improper Verification of Cryptographic Signature vulnerability in Decryption of AES-GCM encrypted JSON Web Tokens that can result in Attacker can forge a authentication tag. This attack appear to be exploitable via network connectivity. This vulnerability appears to have been fixed in 1.9.4 and later."
          }
        ]
      },
      "problemtype": {
        "problemtype_data": [
          {
            "description": [
              {
                "lang": "eng",
                "value": "n/a"
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      },
      "references": {
        "reference_data": [
          {
            "name": "https://github.com/nov/json-jwt/pull/62",
            "refsource": "MISC",
            "url": "https://github.com/nov/json-jwt/pull/62"
          },
          {
            "name": "DSA-4283",
            "refsource": "DEBIAN",
            "url": "https://www.debian.org/security/2018/dsa-4283"
          }
        ]
      }
    },
    "github.com/rubysec/ruby-advisory-db": {
      "cve": "2018-1000539",
      "cvss_v3": 5.3,
      "date": "2018-04-30",
      "description": "Ruby\u0027s OpenSSL bindings do not check the length of the supplied\nauthentication tag when decrypting an authenticated encryption mode\nsuch as AES-GCM, leaving this up to the authors of a gem/app to\nimplement for properly validating the message.\n\njson-jwt was not checking for the authentication tag length, meaning\nthat with a one byte tag the JWT would be considered not tampered\nwith. This means that with an average of 128 (max 256) attempts an\nattacker can forge a valid signature.\n",
      "gem": "json-jwt",
      "ghsa": "mj4x-wcxf-hm8x",
      "patched_versions": [
        "\u003e= 1.9.4"
      ],
      "title": "Auth tag forgery vulnerability with AES-GCM encrypted JWT",
      "unaffected_versions": [
        "\u003c 0.5.1"
      ],
      "url": "https://github.com/nov/json-jwt/pull/62"
    },
    "gitlab.com": {
      "advisories": [
        {
          "affected_range": "\u003e=0.5.0 \u003c1.9.4",
          "affected_versions": "All versions starting from 0.5.0 before 1.9.4",
          "cvss_v2": "AV:N/AC:L/Au:N/C:N/I:P/A:N",
          "cvss_v3": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
          "cwe_ids": [
            "CWE-1035",
            "CWE-347",
            "CWE-937"
          ],
          "date": "2018-09-02",
          "description": "`json-jwt` is vulnerable to improper verification of cryptographic signatures when decrypting AES-GCM encrypted JSON Web Tokens. This can result in an attacker being able to forge an authentication tag.",
          "fixed_versions": [
            "1.9.4"
          ],
          "identifier": "CVE-2018-1000539",
          "identifiers": [
            "CVE-2018-1000539"
          ],
          "not_impacted": "All versions before 0.5.0, all versions starting from 1.9.4",
          "package_slug": "gem/json-jwt",
          "pubdate": "2018-06-26",
          "solution": "Upgrade to version 1.9.4 or above.",
          "title": "Improper Verification of Cryptographic Signature",
          "urls": [
            "https://nvd.nist.gov/vuln/detail/CVE-2018-1000539"
          ],
          "uuid": "391c843a-cf49-4660-b5b0-e7178d0f1377"
        }
      ]
    },
    "nvd.nist.gov": {
      "configurations": {
        "CVE_data_version": "4.0",
        "nodes": [
          {
            "children": [],
            "cpe_match": [
              {
                "cpe23Uri": "cpe:2.3:a:json-jwt_project:json-jwt:*:*:*:*:*:*:*:*",
                "cpe_name": [],
                "versionEndExcluding": "1.9.4",
                "versionStartIncluding": "0.5.0",
                "vulnerable": true
              }
            ],
            "operator": "OR"
          }
        ]
      },
      "cve": {
        "CVE_data_meta": {
          "ASSIGNER": "cve@mitre.org",
          "ID": "CVE-2018-1000539"
        },
        "data_format": "MITRE",
        "data_type": "CVE",
        "data_version": "4.0",
        "description": {
          "description_data": [
            {
              "lang": "en",
              "value": "Nov json-jwt version \u003e= 0.5.0 \u0026\u0026 \u003c 1.9.4 contains a CWE-347: Improper Verification of Cryptographic Signature vulnerability in Decryption of AES-GCM encrypted JSON Web Tokens that can result in Attacker can forge a authentication tag. This attack appear to be exploitable via network connectivity. This vulnerability appears to have been fixed in 1.9.4 and later."
            }
          ]
        },
        "problemtype": {
          "problemtype_data": [
            {
              "description": [
                {
                  "lang": "en",
                  "value": "CWE-347"
                }
              ]
            }
          ]
        },
        "references": {
          "reference_data": [
            {
              "name": "https://github.com/nov/json-jwt/pull/62",
              "refsource": "MISC",
              "tags": [
                "Third Party Advisory"
              ],
              "url": "https://github.com/nov/json-jwt/pull/62"
            },
            {
              "name": "DSA-4283",
              "refsource": "DEBIAN",
              "tags": [],
              "url": "https://www.debian.org/security/2018/dsa-4283"
            }
          ]
        }
      },
      "impact": {
        "baseMetricV2": {
          "cvssV2": {
            "accessComplexity": "LOW",
            "accessVector": "NETWORK",
            "authentication": "NONE",
            "availabilityImpact": "NONE",
            "baseScore": 5.0,
            "confidentialityImpact": "NONE",
            "integrityImpact": "PARTIAL",
            "vectorString": "AV:N/AC:L/Au:N/C:N/I:P/A:N",
            "version": "2.0"
          },
          "exploitabilityScore": 10.0,
          "impactScore": 2.9,
          "obtainAllPrivilege": false,
          "obtainOtherPrivilege": false,
          "obtainUserPrivilege": false,
          "severity": "MEDIUM",
          "userInteractionRequired": false
        },
        "baseMetricV3": {
          "cvssV3": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
            "version": "3.0"
          },
          "exploitabilityScore": 3.9,
          "impactScore": 1.4
        }
      },
      "lastModifiedDate": "2018-09-02T10:29Z",
      "publishedDate": "2018-06-26T16:29Z"
    }
  }
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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