Damn Vulnerable DeFi — Challenge #7 Walkthrough
4 min readJan 24, 2021
Oracles play a critical role in many DeFi applications where they are used to correctly report asset prices and other data. As evident by many incidents such as Cheese Bank and Warp Finance, any oracle price manipulations can lead to multi-million losses. The next Damn Vulnerable DeFi challenge offers a plausible scenario where a price Oracle platform appears to leak potentially sensitive data:
While poking around a web service of one of the most popular DeFi projects in the space, you get a somewhat strange response from their server. This is a snippet:HTTP/2 200 OK
content-type: text/html
content-language: en
vary: Accept-Encoding
server: cloudflare
4d 48 68 6a 4e 6a 63 34 5a 57 59 78 59 57 45 30 4e 54 5a 6b 59 54 59 31 59 7a 5a 6d 59 7a 55 34 4e 6a 46 6b 4e 44 51 34 4f 54 4a 6a 5a 47 5a 68 59 7a 42 6a 4e 6d 4d 34 59 7a 49 31 4e 6a 42 69 5a 6a 42 6a 4f 57 5a 69 59 32 52 68 5a 54 4a 6d 4e 44 63 7a 4e 57 45 35
4d 48 67 79 4d 44 67 79 4e 44 4a 6a 4e 44 42 68 59 32 52 6d 59 54 6c 6c 5a 44 67 34 4f 57 55 32 4f 44 56 6a 4d 6a 4d 31 4e 44 64 68 59 32 4a 6c 5a 44 6c 69 5a 57 5a 6a 4e 6a 41 7a 4e 7a 46 6c 4f 54 67 33 4e 57 5a 69 59 32 51 33 4d 7a 59 7a 4e 44 42 69 59 6a 51 34A related on-chain exchange is selling (absurdly overpriced) collectibles called "DVNFT", now at 999 ETH eachThis price is fetched from an on-chain oracle, and is based on three trusted reporters…
