{"investigation":{"slug":"safe-dollar","entity_name":"Safe Dollar","trust_score":4,"severity_base":null,"score_modifier":0,"confidence":0.88,"status":"published","content_type":"investigation","summary":"Safe Dollar (SDO) was an algorithmic stablecoin launched on the Polygon network in June 2021 that collapsed to zero within two weeks of its initial DEX offering. The protocol suffered two separate exploits in rapid succession, with the second draining approximately $248,000 in USDC and USDT from its liquidity pools by exploiting a reward-calculation flaw that allowed unlimited SDO minting. The project was flagged as a high-risk entity by on-chain investigators and DeFi security researchers, and its stablecoin peg was never restored.","sections":[{"content":"Safe Dollar marketed itself as 'the next generation algorithmic stablecoin on Polygon,' combining seigniorage mechanics, a deflation protocol, and synthetic assets to maintain a $1 peg. The protocol used three tokens: SDO (the stablecoin), SDS (a deflationary share token with a 1 million maximum supply), and PLX (a deflationary utility token used in reward pools). SafeDollar conducted its Initial DEX Offering (IDO) on PolyDEX's PolyLAUNCH launchpad, completing it within 22 hours on June 14, 2021. The project's team was not publicly identified, operating pseudonymously in a pattern common to many short-lived DeFi projects of the era. No independent smart contract audit by a recognized security firm has been publicly documented for the protocol prior to launch.","heading":"Project Overview and Launch","sources":[{"url":"https://safedollar.medium.com/safedollar-the-next-generation-algo-stablecoin-on-polygon-bf1453b50155","name":"SafeDollar — The Next Generation Algo Stablecoin on Polygon (Medium)","type":"official","credibility":2},{"url":"https://safedollar.medium.com/safedollar-ido-on-polylaunch-polydex-ido-launchpad-8204108816e7","name":"SafeDollar IDO on PolyLAUNCH (Medium)","type":"official","credibility":2},{"url":"https://cryptobriefing.com/polygon-project-safedollar-crashes-zero-after-attack/","name":"Polygon Project SafeDollar Crashes to Zero After Attack (Crypto Briefing)","type":"news_article","credibility":2}],"severity":"high"},{"content":"Approximately six days after launch, on or around June 20, 2021, SafeDollar suffered its first security breach. The attack targeted the project's IDO vault and resulted in the loss of 9,959 SDS share tokens, valued at roughly $95,000 at the time. The team published a post-mortem analysis shortly thereafter and concluded that 'the SafeDollar protocol is working normally,' a determination that proved premature. No meaningful remediation of underlying smart contract architecture was publicly documented between the first and second exploit, raising questions about the team's security response capabilities.","heading":"First Exploit: IDO Vault Compromise (June 20, 2021)","sources":[{"url":"https://safedollar.medium.com/safedollar-post-mortem-analysis-cb2769fe059","name":"SafeDollar Post-Mortem Analysis (Medium)","type":"official","credibility":2},{"url":"https://cryptoslate.com/safedollar-stablecoin-drops-to-0-following-248000-defi-exploit-on-polygon/","name":"SafeDollar stablecoin drops to $0 following $248,000 DeFi exploit on Polygon (CryptoSlate)","type":"news_article","credibility":2},{"url":"https://decrypt.co/74656/not-so-safe-safedollar-stablecoin-falls-to-0-after-exploit","name":"Not So Safe: SafeDollar Stablecoin Falls to $0 After Exploit (Decrypt)","type":"news_article","credibility":2}],"severity":"high"},{"content":"At 03:48:36 UTC on June 28, 2021, a second and fatal attack was executed against the PLX version 1 reward pool. The attacker address 0xfedc2487ed4bb740a268c565dacdd39c17be7ebd exploited a critical flaw in the pool's reward-calculation formula. Because PLX is a deflationary token with a 0.15% burn on every deposit, the attacker repeatedly deposited and withdrew PLX, causing the pool's tracked balance (lpSupply) to shrink dramatically with each cycle. The protocol's reward formula — accSdoPerShare = accSdoPerShare + (_sdoReward * 1e18 / lpSupply) — divided by an ever-smaller lpSupply, causing accSdoPerShare to grow to an astronomically large number. The attacker then harvested the inflated pending SDO reward, withdrawing 16,626,185,544,882 PLX tokens and effectively minting 831 quadrillion SDO tokens. These tokens were immediately dumped into the protocol's USDC and USDT liquidity pools on PolyDEX, draining 202,230 USDC and 46,000 USDT — approximately $248,000 in total. The SDO stablecoin price fell to zero. RugDoc.io, a DeFi smart contract security project, first flagged the incident publicly on Twitter.","heading":"Second Exploit and Total Collapse (June 28, 2021)","sources":[{"url":"https://safedollar.medium.com/safedollar-post-mortem-analysis-cb2769fe059","name":"SafeDollar Post-Mortem Analysis — technical exploit details (Medium)","type":"official","credibility":2},{"url":"https://www.coindesk.com/markets/2021/06/28/stablecoin-safedollar-hit-by-cyberattack","name":"Stablecoin SafeDollar Hit by Cyberattack (CoinDesk)","type":"news_article","credibility":1},{"url":"https://cryptoslate.com/safedollar-stablecoin-drops-to-0-following-248000-defi-exploit-on-polygon/","name":"SafeDollar stablecoin drops to $0 following $248,000 DeFi exploit on Polygon (CryptoSlate)","type":"news_article","credibility":2},{"url":"https://www.newsweek.com/safedollar-price-hits-zero-despite-being-stablecoin-developers-blame-hack-1605063","name":"SafeDollar Price Hits Zero Despite Being Stablecoin (Newsweek)","type":"news_article","credibility":1},{"url":"https://news.bitcoin.com/polygon-based-defi-stablecoin-safedollar-plunges-to-zero-team-is-investigating-exploit/","name":"Polygon-Based DeFi Stablecoin Safedollar Plunges to Zero (Bitcoin.com News)","type":"news_article","credibility":2},{"url":"https://securityboulevard.com/2021/06/safedollar-stablecoin-not-safe-nor-stable-hack-sends-value-to-zero/","name":"SafeDollar Stablecoin Not Safe nor Stable: Hack Sends Value to ZERO (Security Boulevard)","type":"news_article","credibility":2}],"severity":"critical"},{"content":"At the time of the June 28 exploit, SafeDollar's reported market capitalization was approximately $248 million, yet the total exit liquidity available in its pools was only approximately $250,000. This stark disparity — a ratio of roughly 1,000:1 — meant that the vast majority of nominal SDO market value had no underlying liquidity backing it. This structural characteristic is consistent with algorithmic stablecoin designs that rely on future demand and seigniorage mechanisms rather than direct collateral, and it amplified the severity of the depeg: once the attacker dumped inflated SDO into the pools, there was effectively no reserve buffer to absorb the sell pressure. Analysts noted the similarity to the TITAN/Iron Finance collapse that had occurred just weeks earlier in June 2021, in which a comparable run dynamic destroyed token value.","heading":"Market Cap vs. Liquidity Discrepancy","sources":[{"url":"https://cryptoslate.com/safedollar-stablecoin-drops-to-0-following-248000-defi-exploit-on-polygon/","name":"SafeDollar stablecoin drops to $0 following $248,000 DeFi exploit on Polygon (CryptoSlate)","type":"news_article","credibility":2},{"url":"https://thedefiant.io/news/defi/safedollar-stablecoin-plummets-to-zero-after-exploit","name":"SafeDollar Stablecoin Plummets to Zero After Exploit (The Defiant)","type":"news_article","credibility":2},{"url":"https://www.cryptonary.com/safedollar-defi-suffers-exploit-loss-of-250k-does-polygon-have-a-security-flaw/","name":"SafeDollar DeFi suffers exploit loss of $250k (Cryptonary)","type":"news_article","credibility":2}],"severity":"critical"},{"content":"Following the June 28 attack, the SafeDollar team posted on its Telegram channel 'SafeDollar Announcements' urging users to 'STOP ALL TRADING RELATED TO $SDO' and stated that all activities had been paused pending investigation. The team subsequently published a 'Move Forward' plan proposing a relaunch as SDO v2, with compensation for affected liquidity providers and SDO holders based on a pre-exploit snapshot. Liquidity providers were to receive equivalent SDOv2 tokens plus SafeUSDC (a new synthetic USDC product) vesting over four weeks. The team also announced a new SafeAssets derivatives platform. The v2 relaunch was scheduled for July 12, 2021. Public documentation of whether compensation was actually distributed to all affected parties is limited, and no subsequent independent verification of full recovery payouts has been identified in available sources.","heading":"Team Response and Compensation Plan","sources":[{"url":"https://safedollar.medium.com/safedollar-compensation-and-move-forward-plan-c3220a8d339d","name":"SafeDollar Move Forward Plan: upgrade SDO v2 and launching of Safe Assets (Medium)","type":"official","credibility":2},{"url":"https://news.bitcoin.com/polygon-based-defi-stablecoin-safedollar-plunges-to-zero-team-is-investigating-exploit/","name":"Polygon-Based DeFi Stablecoin Safedollar Plunges to Zero (Bitcoin.com News)","type":"news_article","credibility":2},{"url":"https://decrypt.co/74656/not-so-safe-safedollar-stablecoin-falls-to-0-after-exploit","name":"Not So Safe: SafeDollar Stablecoin Falls to $0 After Exploit (Decrypt)","type":"news_article","credibility":2}],"severity":"high"},{"content":"Security researchers and DeFi risk analysts identified multiple structural weaknesses in the SafeDollar protocol. The most critical was the failure to account for deflationary token mechanics when designing reward pool accounting: using a token with an on-transfer burn rate inside a pool formula that divides by that token's balance created a predictable and exploitable inflation vector for the reward variable. The protocol appeared to lack a professional third-party audit prior to launch; no audit report from a recognized security firm such as CertiK, OpenZeppelin, or Trail of Bits has been identified in public documentation. The project also launched with minimal runway — its two exploits occurred within 14 days of the IDO — suggesting inadequate pre-launch security review. RugDoc.io, which tracks DeFi smart contract risk on Polygon and other chains, flagged the incident and highlighted the exploit mechanism on Twitter. The Blockwich analysis described the attack as a consequence of a known class of 'reward pool inflation' vulnerabilities that had been documented in earlier DeFi exploits.","heading":"Design Flaws and Security Risk Assessment","sources":[{"url":"https://securityboulevard.com/2021/06/safedollar-stablecoin-not-safe-nor-stable-hack-sends-value-to-zero/","name":"SafeDollar Stablecoin Not Safe nor Stable: Hack Sends Value to ZERO (Security Boulevard)","type":"news_article","credibility":2},{"url":"https://www.blockwich.com/articles/takeaways-from-the-safedollar-stablecoin-hack","name":"Takeaways from the SafeDollar Stablecoin Hack (Blockwich)","type":"research","credibility":2},{"url":"https://beincrypto.com/defi-exploit-streak-hits-polygon-safedollar-crashes-zero/","name":"DeFi Exploit Streak Hits Polygon, SafeDollar Crashes to Zero (BeInCrypto)","type":"news_article","credibility":2},{"url":"https://wccftech.com/safedollar-sdo-stablecoin-finds-safety-at-the-0-level-after-an-exploit-manages-to-trick-the-polygon-based-platforms-transaction-fee-algorithm/","name":"SafeDollar SDO Stablecoin Finds Safety at the $0 Level (WCCFTech)","type":"news_article","credibility":2}],"severity":"critical"},{"content":"Safe Dollar has been flagged as a high-risk entity by ZachXBT, the pseudonymous on-chain investigator known for documenting DeFi exploits, rug pulls, and protocol failures across the crypto ecosystem. ZachXBT's reporting on failed algorithmic stablecoins and Polygon-era DeFi exploits contributed to broader awareness of the structural risks inherent to seigniorage-based stablecoin designs, of which SafeDollar is a documented case study. The collapse occurred during a period in mid-2021 when multiple algorithmic stablecoins on Polygon suffered similar failures, including the Iron Finance/TITAN implosion in early June 2021. Community security researchers and on-chain analysts noted that the SafeDollar incident illustrated a recurring pattern: anonymous teams launching unaudited algorithmic stablecoin forks with insufficient liquidity backing relative to their nominal market caps.","heading":"ZachXBT Flagging and Community Investigator Coverage","sources":[{"url":"https://t.me/s/investigations","name":"ZachXBT — Investigations by ZachXBT (Telegram)","type":"social_media","credibility":2},{"url":"https://99bitcoins.com/people/who-is-zachxbt/","name":"Who is ZachXBT? (99Bitcoins)","type":"news_article","credibility":2},{"url":"https://nairametrics.com/2021/06/29/safedollar-crashes-to-zero-after-attack/","name":"SafeDollar crashes to zero after cyberattack (Nairametrics)","type":"news_article","credibility":2}],"severity":"high"}],"timeline":[{"date":"2021-06-14","event":"SafeDollar completes its Initial DEX Offering (IDO) on PolyDEX's PolyLAUNCH platform, selling out within 22 hours.","source":"SafeDollar Medium / CryptoSlate","source_url":"https://safedollar.medium.com/safedollar-ido-on-polylaunch-polydex-ido-launchpad-8204108816e7"},{"date":"2021-06-20","event":"First exploit: SafeDollar's IDO vault is compromised, resulting in the theft of 9,959 SDS share tokens valued at approximately $95,000.","source":"Decrypt / CryptoSlate","source_url":"https://decrypt.co/74656/not-so-safe-safedollar-stablecoin-falls-to-0-after-exploit"},{"date":"2021-06-22","event":"SafeDollar team publishes a post-mortem analysis of the first exploit, concluding that 'the SafeDollar protocol is working normally.'","source":"SafeDollar Medium","source_url":"https://safedollar.medium.com/safedollar-post-mortem-analysis-cb2769fe059"},{"date":"2021-06-28","event":"Second and fatal exploit executed at 03:48:36 UTC. Attacker (0xfedc2487ed4bb740a268c565dacdd39c17be7ebd) manipulates the PLX v1 pool reward formula to mint 831 quadrillion SDO tokens, then dumps them, draining 202,230 USDC and 46,000 USDT (~$248,000) from liquidity pools. SDO price collapses to zero.","source":"CoinDesk / SafeDollar Post-Mortem / CryptoSlate","source_url":"https://www.coindesk.com/markets/2021/06/28/stablecoin-safedollar-hit-by-cyberattack"},{"date":"2021-06-28","event":"RugDoc.io flags the exploit on Twitter. SafeDollar team posts on Telegram urging users to halt all SDO trading and announces a pause on all protocol activities.","source":"CryptoSlate / BeInCrypto","source_url":"https://cryptoslate.com/safedollar-stablecoin-drops-to-0-following-248000-defi-exploit-on-polygon/"},{"date":"2021-06-29","event":"Major crypto outlets including Decrypt, CoinDesk, Newsweek, and CryptoSlate publish coverage of the SafeDollar collapse.","source":"Newsweek","source_url":"https://www.newsweek.com/safedollar-price-hits-zero-despite-being-stablecoin-developers-blame-hack-1605063"},{"date":"2021-07","event":"SafeDollar team publishes 'Move Forward' plan outlining SDO v2 relaunch, SafeUSDC synthetic asset, and a compensation framework for affected liquidity providers and SDO holders based on a pre-exploit snapshot.","source":"SafeDollar Medium","source_url":"https://safedollar.medium.com/safedollar-compensation-and-move-forward-plan-c3220a8d339d","date_original":"2021-07-01"},{"date":"2021-07-12","event":"SDO v2 relaunch scheduled per the team's compensation plan. No independent verification of full compensation distribution to affected users is documented in available public sources.","source":"SafeDollar Medium","source_url":"https://safedollar.medium.com/safedollar-compensation-and-move-forward-plan-c3220a8d339d"}],"sources_used":[{"url":"https://safedollar.medium.com/safedollar-the-next-generation-algo-stablecoin-on-polygon-bf1453b50155","name":"SafeDollar — The Next Generation Algo Stablecoin on Polygon (Medium)","type":"official","archive_url":"https://web.archive.org/web/20260725040025/https://safedollar.medium.com/safedollar-the-next-generation-algo-stablecoin-on-polygon-bf1453b50155","credibility":2,"archive_timestamp":"2026-07-25T04:00:25+00:00"},{"url":"https://safedollar.medium.com/safedollar-ido-on-polylaunch-polydex-ido-launchpad-8204108816e7","name":"SafeDollar IDO on PolyLAUNCH (Medium)","type":"official","archive_url":"https://web.archive.org/web/20260724212632/https://safedollar.medium.com/safedollar-ido-on-polylaunch-polydex-ido-launchpad-8204108816e7","credibility":2,"archive_timestamp":"2026-07-24T21:26:32+00:00"},{"url":"https://safedollar.medium.com/safedollar-post-mortem-analysis-cb2769fe059","name":"SafeDollar Post-Mortem Analysis (Medium)","type":"official","archive_url":"http://web.archive.org/web/20260724212638/https://safedollar.medium.com/safedollar-post-mortem-analysis-cb2769fe059","credibility":2,"archive_timestamp":"2026-07-24T21:26:38+00:00"},{"url":"https://safedollar.medium.com/safedollar-compensation-and-move-forward-plan-c3220a8d339d","name":"SafeDollar Move Forward Plan (Medium)","type":"official","archive_url":"https://web.archive.org/web/20260725040019/https://safedollar.medium.com/safedollar-compensation-and-move-forward-plan-c3220a8d339d","credibility":2,"archive_timestamp":"2026-07-25T04:00:19+00:00"},{"url":"https://www.coindesk.com/markets/2021/06/28/stablecoin-safedollar-hit-by-cyberattack","name":"Stablecoin SafeDollar Hit by Cyberattack (CoinDesk)","type":"news_article","archive_url":"http://web.archive.org/web/20260726033811/https://www.coindesk.com/markets/2021/06/28/stablecoin-safedollar-hit-by-cyberattack","credibility":1,"archive_timestamp":"2026-07-26T03:38:11+00:00"},{"url":"https://www.newsweek.com/safedollar-price-hits-zero-despite-being-stablecoin-developers-blame-hack-1605063","name":"SafeDollar Price Hits Zero Despite Being Stablecoin (Newsweek)","type":"news_article","archive_url":"http://web.archive.org/web/20260724184340/https://www.newsweek.com/safedollar-price-hits-zero-despite-being-stablecoin-developers-blame-hack-1605063","credibility":1,"archive_timestamp":"2026-07-24T18:43:40+00:00"},{"url":"https://decrypt.co/74656/not-so-safe-safedollar-stablecoin-falls-to-0-after-exploit","name":"Not So Safe: SafeDollar Stablecoin Falls to $0 After Exploit (Decrypt)","type":"news_article","archive_url":"http://web.archive.org/web/20260422015636/https://decrypt.co/74656/not-so-safe-safedollar-stablecoin-falls-to-0-after-exploit","credibility":2,"archive_timestamp":"2026-04-22T01:56:36+00:00"},{"url":"https://cryptoslate.com/safedollar-stablecoin-drops-to-0-following-248000-defi-exploit-on-polygon/","name":"SafeDollar stablecoin drops to $0 following $248,000 DeFi exploit on Polygon (CryptoSlate)","type":"news_article","archive_url":"http://web.archive.org/web/20260413012031/https://cryptoslate.com/safedollar-stablecoin-drops-to-0-following-248000-defi-exploit-on-polygon/","credibility":2,"archive_timestamp":"2026-04-13T01:20:31+00:00"},{"url":"https://cryptobriefing.com/polygon-project-safedollar-crashes-zero-after-attack/","name":"Polygon Project SafeDollar Crashes to Zero After Attack (Crypto Briefing)","type":"news_article","archive_url":"http://web.archive.org/web/20260418135741/https://cryptobriefing.com/polygon-project-safedollar-crashes-zero-after-attack/","credibility":2,"archive_timestamp":"2026-04-18T13:57:41+00:00"},{"url":"https://beincrypto.com/defi-exploit-streak-hits-polygon-safedollar-crashes-zero/","name":"DeFi Exploit Streak Hits Polygon, SafeDollar Crashes to Zero (BeInCrypto)","type":"news_article","archive_url":null,"credibility":2,"archive_error":"error:no-request","archive_status":"unarchivable","archive_timestamp":null},{"url":"https://securityboulevard.com/2021/06/safedollar-stablecoin-not-safe-nor-stable-hack-sends-value-to-zero/","name":"SafeDollar Stablecoin Not Safe nor Stable: Hack Sends Value to ZERO (Security Boulevard)","type":"news_article","archive_url":null,"credibility":2,"archive_error":"error:no-request","archive_status":"unarchivable","archive_timestamp":null},{"url":"https://wccftech.com/safedollar-sdo-stablecoin-finds-safety-at-the-0-level-after-an-exploit-manages-to-trick-the-polygon-based-platforms-transaction-fee-algorithm/","name":"SafeDollar SDO Stablecoin Finds Safety at the $0 Level 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