bsi-2024-0001
Vulnerability from csaf_certbund
Published
2024-04-15 19:00
Modified
2024-04-15 19:00
Summary
Secret Key Recovery of NIST P-521 Private Keys through biased ECDSA nonces in PuTTY client

Notes

Legal disclaimer
As a content provider, BSI is responsible under general law for its own content distributed for use. However, it remains your responsibility to carefully check usage and/or implementation of information provided with the content.
Summary
The PuTTY client and all related components generate heavily biased ECDSA nonces in the case of NIST P-521. This allows for full secret key recovery in roughly 60 signatures by using state-of-the-art techniques. These signatures can either be harvested by a malicious server (machine-in-the-middle attacks are not possible given that clients do not transmit their signature in the clear) or from any other source, e.g. signed git commits through forwarded agents.


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{
  "document": {
    "acknowledgments": [
      {
        "names": [
          "Fabian B\u00e4umer",
          "Marcus Brinkmann"
        ],
        "organization": "Ruhr University Bochum",
        "summary": "finding and reporting the vulnerability"
      }
    ],
    "category": "csaf_security_advisory",
    "csaf_version": "2.0",
    "distribution": {
      "tlp": {
        "label": "WHITE",
        "url": "https://www.first.org/tlp/"
      }
    },
    "lang": "en-US",
    "notes": [
      {
        "category": "legal_disclaimer",
        "text": "As a content provider, BSI is responsible under general law for its own content distributed for use. However, it remains your responsibility to carefully check usage and/or implementation of information provided with the content.",
        "title": "Legal disclaimer"
      },
      {
        "category": "summary",
        "text": "The PuTTY client and all related components generate heavily biased ECDSA nonces in the case of NIST P-521. This allows for full secret key recovery in roughly 60 signatures by using state-of-the-art techniques. These signatures can either be harvested by a malicious server (machine-in-the-middle attacks are not possible given that clients do not transmit their signature in the clear) or from any other source, e.g. signed git commits through forwarded agents.",
        "title": "Summary"
      }
    ],
    "publisher": {
      "category": "coordinator",
      "name": "Bundesamt f\u00fcr Sicherheit in der Informationstechnik",
      "namespace": "https://www.bsi.bund.de"
    },
    "references": [
      {
        "category": "self",
        "summary": "BSI-2024-0001 - CSAF Version",
        "url": "https://wid.cert-bund.de/.well-known/csaf/white/2024/bsi-2024-0001.json"
      }
    ],
    "title": "Secret Key Recovery of NIST P-521 Private Keys through biased ECDSA nonces in PuTTY client",
    "tracking": {
      "current_release_date": "2024-04-15T19:00:00.000Z",
      "generator": {
        "date": "2024-04-15T06:53:52.394Z",
        "engine": {
          "name": "Secvisogram",
          "version": "2.5.2"
        }
      },
      "id": "BSI-2024-0001",
      "initial_release_date": "2024-04-15T19:00:00.000Z",
      "revision_history": [
        {
          "date": "2024-04-15T19:00:00.000Z",
          "number": "1",
          "summary": "Initial version."
        }
      ],
      "status": "final",
      "version": "1"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "\u003e=0.68|\u003c=0.80",
                "product": {
                  "name": "PuTTY client 0.68 - 0.80",
                  "product_id": "CSAFPID-0001"
                }
              },
              {
                "category": "product_version",
                "name": "0.81",
                "product": {
                  "name": "PuTTY client 0.81",
                  "product_id": "CSAFPID-0002"
                }
              }
            ],
            "category": "product_name",
            "name": "PuTTY"
          }
        ],
        "category": "vendor",
        "name": "PuTTY"
      },
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "\u003e=3.24.1|\u003c=3.66.5",
                "product": {
                  "name": "FileZilla Client 3.24.1 - 3.66.5",
                  "product_id": "CSAFPID-0003"
                }
              },
              {
                "category": "product_version",
                "name": "3.67.0",
                "product": {
                  "name": "FileZilla Client 3.67.0",
                  "product_id": "CSAFPID-0004"
                }
              }
            ],
            "category": "product_name",
            "name": "FileZilla Client"
          }
        ],
        "category": "vendor",
        "name": "FileZilla"
      },
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "\u003e=5.9.5|\u003c=6.3.2",
                "product": {
                  "name": "WinSCP 5.9.5 - 6.3.2",
                  "product_id": "CSAFPID-0005"
                }
              },
              {
                "category": "product_version",
                "name": "6.3.3",
                "product": {
                  "name": "WinSCP 6.3.3",
                  "product_id": "CSAFPID-0010"
                }
              }
            ],
            "category": "product_name",
            "name": "WinSCP"
          }
        ],
        "category": "vendor",
        "name": "WinSCP"
      },
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "\u003e=2.4.0.2|\u003c=2.15.0.0",
                "product": {
                  "name": "TortoiseGit 2.4.0.2 - 2.15.0.0",
                  "product_id": "CSAFPID-0006"
                }
              },
              {
                "category": "product_version",
                "name": "2.15.0.1",
                "product": {
                  "name": "TortoiseGit 2.15.0.1",
                  "product_id": "CSAFPID-0007"
                }
              }
            ],
            "category": "product_name",
            "name": "TortoiseGit"
          }
        ],
        "category": "vendor",
        "name": "TortoiseGit"
      },
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "\u003e=1.10.0|\u003c=1.14.6",
                "product": {
                  "name": "TortoiseSVN 1.10.0 - 1.14.6",
                  "product_id": "CSAFPID-0008"
                }
              },
              {
                "category": "product_version",
                "name": "1.14.7",
                "product": {
                  "name": "TortoiseSVN 1.14.7",
                  "product_id": "CSAFPID-0009"
                }
              }
            ],
            "category": "product_name",
            "name": "TortoiseSVN"
          }
        ],
        "category": "vendor",
        "name": "TortoiseSVN"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2024-31497",
      "cwe": {
        "id": "CWE-334",
        "name": "Small Space of Random Values"
      },
      "notes": [
        {
          "category": "description",
          "text": "The PuTTY client and all related components generate heavily biased ECDSA nonces in the case of NIST P-521. This allows for full secret key recovery in roughly 60 signatures by using state-of-the-art techniques. These signatures can either be harvested by a malicious server (machine-in-the-middle attacks are not possible given that clients do not transmit their signature in the clear) or from any other source, e.g. signed git commits through forwarded agents.",
          "title": "CVE description"
        }
      ],
      "product_status": {
        "fixed": [
          "CSAFPID-0002",
          "CSAFPID-0004",
          "CSAFPID-0010",
          "CSAFPID-0007",
          "CSAFPID-0009"
        ],
        "known_affected": [
          "CSAFPID-0001",
          "CSAFPID-0003",
          "CSAFPID-0005",
          "CSAFPID-0006",
          "CSAFPID-0008"
        ]
      },
      "references": [
        {
          "category": "external",
          "summary": "CVE Record",
          "url": "https://cveawg.mitre.org/api/cve/CVE-2024-31497"
        }
      ],
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2024-04-15T19:00:00.000Z",
          "details": "Update to the latest version of the product. At least version 0.61.\nAdditionally, any key material using NIST P-521 must be revoke/discard and new keys have to be generated.",
          "product_ids": [
            "CSAFPID-0001"
          ],
          "url": "https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html"
        },
        {
          "category": "vendor_fix",
          "date": "2024-04-15T19:00:00.000Z",
          "details": "Update to the latest version of the product. At least version 3.67.0.",
          "product_ids": [
            "CSAFPID-0003"
          ],
          "url": "https://filezilla-project.org/download.php?type=client"
        },
        {
          "category": "vendor_fix",
          "date": "2024-04-15T19:00:00.000Z",
          "details": "Update to the latest version of the product. At least version 6.3.3.",
          "product_ids": [
            "CSAFPID-0005"
          ],
          "url": "https://winscp.net/eng/download.php"
        },
        {
          "category": "vendor_fix",
          "date": "2024-04-15T19:00:00.000Z",
          "details": "Update to the latest version of the product. At least version 2.15.0.1.",
          "product_ids": [
            "CSAFPID-0006"
          ],
          "url": "https://tortoisegit.org/download/"
        },
        {
          "category": "workaround",
          "date": "2024-04-15T19:00:00.000Z",
          "details": "As long as there is no official patch available: Configure TortoiseSVN to use PuTTY\u0027s latest plink.exe instead of the included exe. ",
          "product_ids": [
            "CSAFPID-0008"
          ]
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 10,
            "baseSeverity": "CRITICAL",
            "confidentialityImpact": "HIGH",
            "environmentalScore": 10,
            "environmentalSeverity": "CRITICAL",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "temporalScore": 10,
            "temporalSeverity": "CRITICAL",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "products": [
            "CSAFPID-0001"
          ]
        },
        {
          "cvss_v3": {
            "attackComplexity": "LOW",
            "attackVector": "LOCAL",
            "availabilityImpact": "HIGH",
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "environmentalScore": 8.3,
            "environmentalSeverity": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "HIGH",
            "scope": "CHANGED",
            "temporalScore": 8.2,
            "temporalSeverity": "HIGH",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "products": [
            "CSAFPID-0003",
            "CSAFPID-0005",
            "CSAFPID-0006",
            "CSAFPID-0008"
          ]
        }
      ],
      "title": "Secret Key Recovery of NIST P-521 Private Keys through biased ECDSA nonces in PuTTY client"
    }
  ]
}


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