Stellar Circles is a reputation and influence system built on Soroban. Because influence affects decision-making, we must address manipulation, gaming, and attack vectors.

1. Influence scores — manipulated scores can distort decision power
2. Circle membership — unauthorized access or removal
3. Participation records — fake or duplicated activities
4. Decision outcomes — vote manipulation, collusion
5. Admin privileges — unauthorized control transfers

• External — non-members trying to manipulate circles
• Internal — members gaming the system for disproportionate influence
• Colluding groups — coordinated manipulation
• Compromised admins — malicious or hacked admin accounts

Threat: Attacker creates multiple fake identities to gain disproportionate influence.

Mitigations:

• ✅ Stellar account requirement — each member needs a funded Stellar account (small cost barrier)
• 🚧 Admin-approved membership — circles can require invite/approval
• 🚧 Social verification — link to external identity (GitHub, email, etc.)
• 📋 Participation verification — activities require off-chain validation before on-chain recording

Current Status:
Circle contract supports admin control. Membership contract has invite functionality. Need to add verification layer for participation recording.

Residual Risk:
Attacker could still create multiple Stellar accounts. This is expensive at scale but possible. Social verification layer needed.

Threat: Members log activities they didn't actually perform to inflate influence.

Mitigations:

• 📋 Off-chain validation — activities verified by circle admin or oracle before on-chain record
• 📋 Multi-sig requirements — significant activities require approval from 2+ admins
• 📋 Attestation system — other members can vouch for/challenge activities
• 📋 Time-locked recording — activities can only be logged within N hours of occurrence
• 📋 External proofs — link activities to verifiable external events (GitHub commits, GPS check-ins, etc.)

Current Status:
No participation contract yet. This is critical priority for Phase 2.

Residual Risk:
Without external validation, relies on admin honesty. Need robust verification layer.

Threat: Members optimize for influence gain without genuine contribution.

Examples:

• Logging many low-value activities instead of meaningful contributions
• Gaming the streak system by minimal weekly participation
• Exploiting activity weight differences

Mitigations:

• ✅ Quality factor — peer ratings affect influence calculation
• ✅ Diminishing returns — influence growth slows as participation increases
• 🚧 Activity caps — limit how many activities can be logged per day/week
• 🚧 Decay mechanism — 5% weekly decay for inactive members
• 📋 Peer review — members can flag suspicious patterns

Current Status:
Influence model designed with these in mind (see docs/influence-model.md). Implementation pending.

Residual Risk:
Determined attacker can still optimize within the rules. Need ongoing monitoring and formula adjustments.

Threat: Group of members coordinate to manipulate decisions or inflate each other's influence.

Examples:

• Vote brigading — coordinated voting to pass/block proposals
• Mutual endorsement rings — members artificially boost each other's quality scores
• Admin conspiracies — multiple admins collude to manipulate circle

Mitigations:

• ✅ Influence caps — maximum voting weight per member (even with high influence)
• ✅ Square-root dampening — vote weight = √(score/max_score), not linear
• 🚧 Quorum requirements — decisions need minimum % of members to vote
• 🚧 Public audit trail — all votes and participation visible on-chain
• 📋 Anomaly detection — flag unusual voting patterns or endorsement networks
• 📋 Time delays — proposals have minimum deliberation period before voting closes

Current Status:
Vote weighting formula includes dampening. Decision contract not yet implemented.

Residual Risk:
Organized groups can still coordinate. Transparency helps but doesn't prevent.

Threat: Single member or small group accumulates overwhelming influence.

Mitigations:

• ✅ Influence caps — maximum influence score per member
• ✅ Vote weight caps — even max-influence member has limited % of total vote weight
• ✅ Decay — inactive high-influence members lose score over time
• 🚧 Participation requirements — minimum activity level to maintain influence
• 📋 Term limits — admin roles expire after N months (requires re-election)
• 📋 Influence redistribution — decayed influence doesn't disappear, gets redistributed

Current Status:
Caps and decay designed. Implementation pending.

Residual Risk:
Founder effect — early members naturally have more influence. This is somewhat intentional (reward early contributors) but needs monitoring.

Threat: Circle admin acts maliciously or gets compromised.

Examples:

• Removing legitimate members
• Approving fake participation
• Blocking proposals
• Transferring admin to attacker

Mitigations:

• ✅ Authorization checks — all admin functions require signature verification (Soroban native)
• ✅ Multi-admin — circles can have multiple admins (implemented in membership contract)
• 🚧 Admin removal vote — members can vote to remove admin (requires decision contract)
• 🚧 Time delays — admin actions (removals, etc.) have delay period where other admins can veto
• 📋 Admin activity log — transparent on-chain record of all admin actions
• 📋 Emergency pause — contract pause mechanism for suspected compromise

Current Status:
Admin authorization works. Multi-admin supported. Removal/veto mechanisms pending.

Residual Risk:
Single-admin circles are vulnerable. Encourage multi-admin governance.

Threat: Same activity logged multiple times to inflate influence.

Mitigations:

• 📋 Activity IDs — each activity has unique identifier, duplicate IDs rejected
• 📋 Timestamp validation — prevent logging the same activity type within short time window
• 📋 Merkle proofs — activities reference external proof that can't be reused
• 📋 Nonce system — activities include incrementing nonce per member

Current Status:
Not yet implemented (no participation contract yet).

Residual Risk:
Critical to get right in Phase 2. Without this, the whole system breaks.

Threat: Attacker gains access to member's Stellar secret key.

Mitigations:

• ✅ Stellar native security — uses Stellar's account security model
• 📋 Multi-sig accounts — members can use multi-sig Stellar accounts
• 📋 Activity anomaly detection — flag sudden unusual participation patterns
• 📋 Influence freeze — member can freeze their influence if they suspect compromise
• 📋 Recovery mechanism — social recovery to new account with influence transferred

Current Status:
Relies on Stellar security. Application-level protections pending.

Residual Risk:
If wallet compromised, attacker can impersonate member until detected. Need detection + recovery.

Threat: Bugs in Soroban contracts allow unintended behavior.

Mitigations:

• ✅ Comprehensive tests — unit tests for all functions (implemented for circle & membership)
• 🚧 Integration tests — test contract interactions
• 📋 Formal verification — mathematically prove key properties
• 📋 External audit — professional security audit before mainnet
• 📋 Bug bounty — incentivize responsible disclosure
• 📋 Upgrade mechanism — ability to fix bugs without losing state

Current Status:
Unit tests exist. Need integration tests, audit, and upgrade plan.

Residual Risk:
Contracts are immutable once deployed. Bugs are permanent unless upgrade mechanism exists.

Threat: Attacker sees pending decision vote in mempool and submits competing transaction with higher fee.

Mitigations:

• ✅ Stellar fee structure — base fee model reduces front-running incentive
• 🚧 Commit-reveal voting — members commit hash of vote, then reveal later
• 📋 Batch voting — votes processed in batches, reducing MEV opportunity

Current Status:
Not yet relevant (no decision contract). Consider for Phase 3.

Residual Risk:
Less of an issue on Stellar than Ethereum, but still possible.

• ✅ Authorization checks in all contracts
• ✅ Comprehensive unit tests
• ✅ Input validation

• 🚧 Participation verification layer
• 🚧 Influence calculation with caps & decay
• 🚧 Integration tests
• 🚧 Anomaly detection design

• 📋 Decision contract with vote dampening
• 📋 Multi-sig requirements
• 📋 External security audit
• 📋 Bug bounty program

• 📋 Formal verification (critical paths)
• 📋 Social recovery mechanism
• 📋 Upgrade/migration plan
• 📋 Testnet battle-testing

Do not open public issues for security vulnerabilities.

Instead:

1. Email: [security contact to be added]
2. Provide:
   • Description of the vulnerability
   • Steps to reproduce
   • Potential impact
   • Suggested fix (optional)

We will respond within 48 hours and work with you on a fix and disclosure timeline.

Stellar Circles assumes:

1. Soroban platform security — we trust Stellar's VM and consensus
2. Stellar account security — members protect their secret keys
3. Off-chain coordination — some verification happens outside smart contracts
4. Admin honesty — circles with single admins trust that admin
5. Rational actors — gaming the system is more expensive than legitimate participation

If any of these assumptions break, the system may not provide intended guarantees.

Security is an ongoing process. This document will evolve as:

• Contracts are implemented and tested
• Attack vectors are discovered
• Mitigation strategies are deployed
• Community feedback is received

Current priority: Implement participation verification layer with robust anti-duplication and validation mechanisms.

Last updated: 2025-01-XX