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Insecure service configuration - Container level access policy

Description​

Container level policy is not set when generating a service Shared Access Signature (SAS). A container-level access policy can be modified or revoked at any time. It provides greater flexibility and control over the permissions that are granted

Impact​

Create IDORs, excessive privileges, or broken authentication vulnerabilities

Recommendation​

Specify a valid group policy identifier when generating the service SAS.

Threat​

Authenticated attacker from the Internet

Expected Remediation Time​

⌚ 50 minutes.

Score​

Default score using CVSS 3.1. It may change depending on the context of the src.

Base​

  • Attack vector: N
  • Attack complexity: H
  • Privileges required: L
  • User interaction: N
  • Scope: U
  • Confidentiality: L
  • Integrity: L
  • Availability: N

Temporal​

  • Exploit code maturity: U
  • Remediation level: O
  • Report confidence: R

Result​

  • Vector string: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:R
  • Score:
    • Base: 4.2
    • Temporal: 3.5
  • Severity:
    • Base: Medium
    • Temporal: Low

Score 4.0​

Default score using CVSS 4.0 . It may change depending on the context of the src.

Base 4.0​

  • Attack vector: N
  • Attack complexity: H
  • Attack Requirements: N
  • Privileges required: L
  • User interaction: N
  • Confidentiality (VC): L
  • Integrity (VI): L
  • Availability (VA): N
  • Confidentiality (SC): N
  • Integrity (SI): N
  • Availability (SA): N

Threat 4.0​

  • Exploit maturity: U

Result 4.0​

  • Vector string: CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U
  • Score:
    • CVSS-BT: 0.6
  • Severity:
    • CVSS-BT: Low

Compliant code​

The service SAS is correctly configured with a group policy

var storageAccount = CloudStorageAccount.Parse(connectionString);
var blobClient = storageAccount.CreateCloudBlobClient();

var blobContainer = blobClient.GetContainerReference(containerName);
blobContainer.CreateIfNotExists();

var storedPolicy = new SharedAccessPolicy()
{
  SharedAccessExpiryTime = DateTime.UtcNow.AddHours(10),
  Permissions = SharedAccessBlobPermissions.Read |
                SharedAccessBlobPermissions.Write |
                SharedAccessBlobPermissions.List
  AccessPolicy = groupPolicy();
};

//Define access permissions before generating the key
var permissions = blobContainer.GetPermissions();
permissions.SharedAccessPolicies.Clear();
permissions.SharedAccessPolicies.Add(policyName, storedPolicy);
blobContainer.SetPermissions(permissions);

var containerSignature = blobContainer.GetSharedAccessSignature(null, policyName);
var uri = blobContainer.Uri + containerSignature;

Non compliant code​

The service SAS does not specify any group policy identifier

var storageAccount = CloudStorageAccount.Parse(connectionString);
var blobClient = storageAccount.CreateCloudBlobClient();

var blobContainer = blobClient.GetContainerReference(containerName);
blobContainer.CreateIfNotExists();

var storedPolicy = new SharedAccessPolicy()
{
  SharedAccessExpiryTime = DateTime.UtcNow.AddHours(10),
  Permissions = SharedAccessBlobPermissions.Read |
                SharedAccessBlobPermissions.Write |
                SharedAccessBlobPermissions.List
  AccessPolicy = defaultPolicy();
};
//Generate SAS
var containerSignature = blobContainer.GetSharedAccessSignature(null, policyName);
var uri = blobContainer.Uri + containerSignature;

Requirements​

Fixes​

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