Vanity Address Exploit Drains SIR Trading's Entire $355K Via Transient Storage Collision

SIR Trading (Synthetics Implemented Right), a leverage protocol on Ethereum, lost its entire $355,000 in TVL on March 30, 2025, to an attacker who exploited a collision in the protocol's use of Ethereum's transient storage feature. The protocol had only launched on February 20, giving it barely more than a month of operation before being emptied.

The team disclosed the incident directly: "SIR has been hacked, do not deposit any further funds. We will post more asap." TenArmor Security confirmed the attack shortly after and traced the stolen funds to Railgun, a privacy-focused mixing protocol.

The root cause, according to TenArmor's analysis, was a transient storage collision inside the uniswapV3SwapCallback function: slot 0x1 was being used to store both the Uniswap pool address and the amount of a minted token. Decurity's writeup described it as a deliberate, well-engineered attack on the protocol's Vault contract. The callback was designed to authenticate the caller by checking that transient storage slot 0x1 matched the pool address — but the same function later wrote the mint amount variable into that identical slot, overwriting the verification data with attacker-controlled input.

Security researcher SuplabsYi laid out how this flaw was converted into a working exploit. First, the attacker needed to brute-force a vanity address that, interpreted as a 160-bit number (per Ethereum's addressing scheme, derived from the last 20 bytes of the Keccak-256 hash of a public key), equaled a specific 29-digit value: 95759995883742311247042417521410689. The resulting address, 0x00000000001271551295307acc16ba1e7e0d4281, was reachable with brute-forcing tools such as VanityEth or GPU-based generators, though computationally demanding.

SlowMist's technical breakdown detailed the remaining steps. The attacker deployed malicious tokens and a UniswapV3 pool, then initialized a leverage market inside the Vault contract. When the mint function executed, the protocol used the TSTORE opcode to write the UniswapV3 pool address into transient storage slot 0x1, as intended by its design — but later in the same function, it overwrote that slot with the attacker's precomputed mint amount of 95759995883742311247042417521410689. With storage now poisoned, the attacker deployed an attack contract via CREATE2, deliberately matching its resulting address to that exact value, and then called uniswapV3SwapCallback directly. When the function used TLOAD on slot 0x1 to verify the caller, it read back the attacker's own address rather than the legitimate pool's — satisfying the check and authenticating the attacker as if they were Uniswap itself.

From there, the attacker repeatedly invoked uniswapV3SwapCallback from their malicious contract, draining funds from the Vault with each call, and laundered the proceeds through Railgun.

Attacker's address: 0x27defcfa6498f957918f407ed8a58eba2884768c Vulnerable contract: 0xb91ae2c8365fd45030aba84a4666c4db074e53e7 Attack transaction: 0xa05f047ddfdad9126624c4496b5d4a59f961ee7c091e7b4e38cee86f1335736f

Aftermath

The timing carried an odd coincidence. A day before the exploit, founder Xatarrer had posted a story on X about a prospective developer candidate who, during a video interview, was asked to repeat an insulting phrase about North Korean leader Kim Jong Un as an informal screening test for state-sponsored operatives. According to the post, the candidate's video background briefly glitched to reveal what appeared to be a violent scene, after which the candidate sent a final cryptic message referencing "RPC sync issues" and a "95% LTV" liquidation before disappearing. The account associated with the candidate was identified as xPOSITION.

Hours later, SIR Trading's own treasury was drained. Xatarrer's tone shifted sharply: "Sorry. This is devastating news. I just came back asap from my kid's training. I am in shock. Sorry to everyone. Investors, believers… I poured 4 years of my life. And now we just lost most of the funds to an attacker. I have no words."

The team then reached out to the attacker, offering to let them keep $100,000 — roughly 28% of the stolen $355K — in exchange for returning the rest: "SIR isn't some VC-backed copy-paste DeFi project, but a completely new type of leverage primitive. It's four years of late-night coding, $70k from friends and believers, and we grew to $400k TVL organically without any advertising. If you keep 100% of the funds, there is no chance for us to survive... keep $100k as a fair share for your critical bug find, and return the remaining... No legal games, no drama."

The protocol had undergone a single security audit, conducted by Egis Security in February, which identified several high-severity issues. Xatarrer acknowledged the limitation directly: "We raised around $70k from folks in here which allowed us to do 1 audit which unfortunately wasn't enough." He also noted the project's difficulty securing venture backing: "We have walked alone because I have been basically stonewalled by VCs. Not even getting any feedback. Not sure how we would relaunch from here, but if you have any idea I'm all ears."

As of writing, there was no indication of whether the attacker would accept the bounty offer. The team has since said it lost most of its funds but is attempting a relaunch, seeking auditors willing to work for token equity rather than payment, citing the fact that the underlying product had demonstrably worked in production up to the point of the exploit.

The incident has renewed scrutiny of Ethereum's transient storage feature, introduced as part of the Dencun upgrade. SuplabsYi suggested this may be among the first real-world attacks exploiting the feature's risks, underscoring that transient storage — intended primarily as a gas optimization — can become a serious attack surface when a single storage slot is reused for both authentication and unrelated data without proper isolation.