Geth bug found in Ethereum network

Ethereum developers find Geth bug as hardfork date is coming closer 
15 October 2017   2425

The developers of Ethereum's Geth software release a new version just days before the Byzantium hard fork due to the discovery of a denial-of-service (DoS) attack vulnerability.

Ethereum's Geth 1.7.2
Ethereum's Geth 1.7.2 urgent update

With Geth comprising about 75% of all Ethereum nodes, the vulnerability could leave nodes running the previous Byzantium-compatible release more susceptible to DoS attacks after the hard fork.

Casey Detrio, Ethereum developer, explains on reddit.com that the vulnerability stems from an oversight in one of the new Byzantium features. The risk is that this bug could be exploited by an attacker who wants to take ethereum nodes offline – a form of attack that the Ethereum community has dealt with in the past. 

The second concern is that there may be more undiscovered consensus bugs that could be found after the activation block, which would then result in needing to perform emergency client updates.
 

Casey Detrio
Ethereum developer

It's also worth mentioning, that yesterday, the team behind Parity issued a new release of its software that corrected a "consensus bug" – an error which could have caused the network to partition during the hard fork. 

Constantinople to be Postponed

Ethereum's hardfork will be late due to critical vulnerability found
16 January 2019   79

A scheduled upgrade of the Ethereum network called Constantinople was postponed indefinitely after a critical vulnerability was discovered in one of the improvements, CoinDesk reports.

This is a vulnerability in EIP-1283, which, as identified by the audit company SmartSecurity smart contracts, gave hackers the opportunity to steal user funds.

During a video conference on Tuesday with the participation of Ethereum developers and other clients and projects working on the network, it was decided to temporarily postpone the activation of the hard forks.

In particular, Vitaly Buterin, developers Hudson Jameson, Nick Johnson and Evan van Ness, as well as release manager of Parity Afri Shoedon took part in the meeting. Discussing the revealed vulnerability, they agreed that it would be impossible to eliminate it before the appointed time for hardfork (around 04:00 UTC on January 17).

A vulnerability, called a reentrancy attack, allows an attacker to repeatedly enter the same function and infinitely withdraw funds.

Imagine that my contract has a function which makes a call to another contract… If I’m a hacker and I’m able to trigger function a while the previous function was still executing, I might be able to withdraw funds.
 

Joanes Espanol

CTO, blockchain analytics firm Amberdata

According to him, this is a lot like the vulnerabilities that were discovered in The DAO in the summer of 2016.

Representatives of ChainSecurity also noted that up to the Constantinople hard fork, data storage on the network cost 5,000 units of gas, which exceeds the 2,300 gas usually needed to call the “transfer” and “send” functions. After the upgrade, “dirty” storage operations will cost 200 units of gas, and an attacking contract can use 2,300 gas to successfully manipulate the variables of vulnerable contracts.

New date of hardfork not yet determined.