Mnemonic is no longer safe?

[erep]

When we do talk about mnemonic phrases then based up on experience and hopefully i wont really be able to experience loss of funds.
After a long years of using up my MyEtherwallet (MEW) and Electrum which is really that based on having those phrases
which my assets are still intact or havent lost because i had stored up offline those keys and not into my pc or cloud storage or something like that.

Safety of your assets would be definitely be depending on you.You might believe that you hadnt missed out something
but its impossible that a certain wallet could be bruteforce without knowing those words.
Those are been exposed.

We must save files on external devices to prevent damage to the operating system or to prevent files from being infected with viruses. In other cases, many Newbies do not realize that they have filled in the PK in the airdrop or bounty registration form so that they lose the assets that have been accumulated in their wallet. So there are many factors that mnemonics can be hacked even our own mistakes in copying so as to publish wallet access to others, so anything related to wallet files must be ensured to be stored securely and must be careful to distinguish Public wallet and Private Key.

[serjent05]

I haven't experienced any Mnemonic leak in my device.  I believe all the phrases created within our unit is safe until it is breached by malware.  The leak of this secret phases maybe caused by a malware or virus that snippet wallet and it is possible that @OP friend is infected by cryware[1].  It is said that this malware is designed to collect and exfiltrate data from hot wallets, or non-custodial cryptocurrency wallets, that are stored on common user devices and help complete crypto transactions. [1]  The link below gives more detail about this kind of malware.  It also gives pointers on how to keep our gadgets and devices safe from malware. 
(copy pasted it here to anyone who doesn't want to click the link)

Microsoft has been on the front lines to help protect users against crypto wallet malware. The company has provided a number of tips for protecting users’ hot wallets.

Keep hot wallets locked when the user is not actively trading, and disconnect sites that are connected to the hot wallet.
Do not store private key information in plain text format (which can be easily stolen), and use care when copying and pasting password information.
Terminate a browser session every time a transaction is completed.
Be on the lookout for suspicious links to wallet websites and apps, and double-check crypto wallet transactions and approvals.
Don’t share private key information or seed phrases, and seek out wallets that use multifactor authentication.
Use hardware wallets that store private keys offline.
Double check the full file extensions of files that you download.

[1] https://www.simplilearn.com/malware-and-crypto-wallets-how-hackers-are-exploiting-article#:~:text=A%20new%20threat%20has%20recently,and%20help%20complete%20crypto%20transactions.

[Oilacris]

I haven't experienced any Mnemonic leak in my device.  I believe all the phrases created within our unit is safe until it is breached by malware.  The leak of this secret phases maybe caused by a malware or virus that snippet wallet and it is possible that @OP friend is infected by cryware[1].  It is said that this malware is designed to collect and exfiltrate data from hot wallets, or non-custodial cryptocurrency wallets, that are stored on common user devices and help complete crypto transactions. [1]  The link below gives more detail about this kind of malware.  It also gives pointers on how to keep our gadgets and devices safe from malware. 
(copy pasted it here to anyone who doesn't want to click the link)

Malware or viruses is never been new on digital world.There's always those hackers who would really be keep on making malwares and other related stuff considering that crypto space is something a

honeypot for them to get tons of money with those crawling malwares which we know that majority of us really make use of pc and mobiles which is really that easy to penetrate if you arent that

aware on how these things works or make yourself that safe with it.Its typical but people would only learn up on strengthen up their security once they had
experience some losses.

[JahriMeayer]

This is very first time I'm experiencing with the name of Coin98 wallet! Maybe its an extinction of crome browser, i notice it also available as Coin98 Super apk for mobile device. I don't know how safe this is for generating Mnemonic seed. I suggest to open another Mnemonic seed by using Trust wallet or metamask and transfer funds from others wallets which are created by using Coin98! Cause it also possible those wallets are already compromised and hacker will transfers fund later and recheck your device and make sure that is safe

[harizen]

There might be some part of the story that we didn't know since OP just conclude right away that it's because of mnemonics being not safe. OP should look at all sides of the case starting from the hardware/devices that were used or might be his friend did some unintentional action that is not aware of.

Technically, mnemonics are safe and can't be breached that just easy. Although I'm not really aware of this Coin98 wallet and I'm confused about how on earth your friend ended up with a wallet that I can't even consider as popular or reputable.

[Fivestar4everMVP]

@OP Mnemonic phrase does not prevent a user from being hacked, keeping the mnemonic phrase safe from Hackers is what does prevent a user from hacks.
You already know and stated how and why your friend got hacked, you said he's device was infiltrated by malware, this is more than enough reason to get hacked and lose alot of money, and I thank God for your friend because in his case, he didn't loose much, $300 to $400 I understand is quite a lot for some people, but think of it, people loose millions of dollars in this same simple process.

So to assure you, I tell you that mnemonic are very safe, but also very importantly requires to be kept safe to avoid being hacked.

[Baofeng]

This is very first time I'm experiencing with the name of Coin98 wallet! Maybe its an extinction of crome browser, i notice it also available as Coin98 Super apk for mobile device. I don't know how safe this is for generating Mnemonic seed. I suggest to open another Mnemonic seed by using Trust wallet or metamask and transfer funds from others wallets which are created by using Coin98! Cause it also possible those wallets are already compromised and hacker will transfers fund later and recheck your device and make sure that is safe

I'm also not aware of Coin98 mobile wallet.

There might be some part of the story that we didn't know since OP just conclude right away that it's because of mnemonics being not safe. OP should look at all sides of the case starting from the hardware/devices that were used or might be his friend did some unintentional action that is not aware of.

Technically, mnemonics are safe and can't be breached that just easy. Although I'm not really aware of this Coin98 wallet and I'm confused about how on earth your friend ended up with a wallet that I can't even consider as popular or reputable.

I agree, maybe this is just part of the story, maybe someone the OP's friend has access to his PC and then later found out his mnemonic phrase. So not necessarily a hacked or his PC has malware, it's more of an inside job.

And this is the main reason why you don't do that, saving your mnemonic phrase in a text base or something that is very clear to read and understand by others. Keep it away that only you have access to it.

[samcrypto]

I agree, maybe this is just part of the story, maybe someone the OP's friend has access to his PC and then later found out his mnemonic phrase. So not necessarily a hacked or his PC has malware, it's more of an inside job.

And this is the main reason why you don't do that, saving your mnemonic phrase in a text base or something that is very clear to read and understand by others. Keep it away that only you have access to it.

Either an inside job or a hacking incidents and with this, we can still say that Mnemonic is still a safe option for your wallet all you have to do is to secure it at the best possible way. I wonder if your friend let someone use his computer without him around? This is also why I don't let anyone to access my computer because I value privacy and this is where I secure my wallet details aside from having my own black book. The other option is really to write it down in a secure notebook and have code on that which you are the only one who understand that code.

[Wong Gendheng]

Just want to share, I can't prove that mnemonic safe or not.  I'm not an expert for things like that.

My friend just got hacked, lost about 300-400 USD.

He wonder how it happened, make some probably the device was infiltrated by malware, if yes. All his key is gone(all), so there's no only 1.

He was generated Mnemonic by coin98. Never connected to MetaMask or some things like login to connected, never.

Address land to "0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82"

0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82 has lot network. There's 5 I found. https://blockscan.com/address/0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82

ETH  https://etherscan.io/address/0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82
BSC  https://bscscan.com/address/0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82
Poly https://polygonscan.com/address/0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82
OP https://optimistic.etherscan.io/address/0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82
ARBI https://arbiscan.io/address/0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82

Take a sample :

Code:

	Txn Hash	Age	From		To	Value	Token
0x3cf166bd6c86b610162daa81f1cbc3dba78383fdd6399eac3091f1e1266158e6	1 hr 21 mins ago	0x46db46fca91287acada4669788ea0e0e6fccc4d6	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	1,000	DEXTools (DEXT)
0x12449d639d36ff5360bf2ef507175ac0d2d7ee4b28397f0841d7b7760fe9cd00	1 hr 21 mins ago	0x46db46fca91287acada4669788ea0e0e6fccc4d6	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	0.124008	Wrapped Ethe... (WETH)
0xe11c041c8a3a34cb4c3127ef16c9ac42c144d76a825c962998187634d13cbae3	1 hr 33 mins ago	ENS Name sircryptoofblock.eth	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	0.02358337	Governance O... (gOHM)
0x1f56d27daaf2eb9ea62a34488a52ba1290f67c5c69bff3e1470a20466861a031	1 hr 34 mins ago	ENS Name sircryptoofblock.eth	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	16.55468149	Ethereum Nam... (ENS)
0xec5390bed60aec9deeea96e9518b20b21959a1e5a03eaf983008616656357ce1	1 hr 34 mins ago	ENS Name sircryptoofblock.eth	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	0.5	Wrapped Ethe... (WETH)
0x4486b49d823e35d72194cfb1103dff731d917ecc302e0c39f1feced1d0cad3df	1 hr 35 mins ago	ENS Name sircryptoofblock.eth	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	166.78365256	StargateToke... (STG)
0xd80d62c04f17f25d7481acfc2b10e7358337751580991b26031083386ee2ee37	1 hr 54 mins ago	0xea1256ad1cc8144c09aebe19217daedc2fb6c655	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	1.09542125	Wrapped Ethe... (WETH)
0xf3bb3f7954b5b85bb4d9dd3d691d72fd1eb8cc18be23c55440bbb52a31fa87bb	1 hr 59 mins ago	0xea1256ad1cc8144c09aebe19217daedc2fb6c655	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	3,325,000	 ERC-20: Met.....yAi
0xd9c4a28c70c551b251876cfa94d0d66181a925f1fd5e75b550ea547ecfd412a1	2 hrs 1 min ago	0x3e99ef9745c7174ef20639b1035b79ed1b8a085e	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	250	Polkastarter... (POLS)
0x19a9516e5dfc3695edfdba696ae2b6527f9384e7e286acd48569a9cd6242eae3	2 hrs 5 mins ago	ENS Name dmuz.eth	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	0.507535	Wrapped Ethe... (WETH)
0xda35ffcb30ebe56c4e3e5303170dfc12ab313bdf653c8b4c4752aecd37d3019d	2 hrs 10 mins ago	ENS Name dmuz.eth	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	1.54064217	Wrapped Ethe... (WETH)
0x94d3ad9ea80dc5df577fa37f25383e049aa98f76715f8df922ad8b51b4bd7663	2 hrs 17 mins ago	ENS Name dmuz.eth	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	1.8296811	Wrapped Ethe... (WETH)
0xef4e4413bb3535c78bce921f9d05814961c3a9b14aa3ace872ac51de20e80644	2 hrs 37 mins ago	0x154eff17af3ae2fe2064fe70fb997d807cf1c011	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	41.99255724	Olympus (OHM)
0xf0b29887ad526399f291462a4b3eef4283001037a3547f5c030b59ccb52fd00a	2 hrs 38 mins ago	0x154eff17af3ae2fe2064fe70fb997d807cf1c011	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	92,976,341,396.66919415	The People’s... (PEEPS)
0xa752e2a30cfdc25107013f9ea2338f2b0eb55ac423762c8a614a08fe6c9d8188	2 hrs 44 mins ago	0x154eff17af3ae2fe2064fe70fb997d807cf1c011	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	3,810,550,290,956.5476974	Bezoge Earth (BEZOGE)
0x7039964c4e99532c75aada210d1d81d7231bc49d7fe268fff4a69d3711e1fdb2	2 hrs 44 mins ago	0x154eff17af3ae2fe2064fe70fb997d807cf1c011	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	41,267.59937671	MintySwap (MINTYS)
0x08aed967fba449b94e5ff4536fba07d25f8ae1a67ff956781dd1e1aedea81bdc	2 hrs 45 mins ago	0x154eff17af3ae2fe2064fe70fb997d807cf1c011	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	49,999.99999716	Falcon 9 (F9)
0xa2223addbef9999d87140a013e751b443bbdde4d459ed6b345b6d925e92aa81e	2 hrs 45 mins ago	0x154eff17af3ae2fe2064fe70fb997d807cf1c011	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	80,462.26	ACCEL (ACCEL)
0xd012dc1d82c7f8cb602a0e1b9d4b0295691431b4aac90c6e5ef0e497e2432769	2 hrs 57 mins ago	0x8090b15679d7b67625f5655883a7e42fad1adffa	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	0.22792	Wrapped Ethe... (WETH)
0xd33bb3f40d8ad5158c5798ea0cf5ea680779a18ee3bf7b7e4f11018ffdb948a0	3 hrs 2 mins ago	0xe9c14ea0d6e9aaa7c58774b05cc6f455cc506bda	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	246.6231	Ultra Token (UOS)
0x56909ca1b3b820959a45daa3792c7002d7786be28821b0f3c32e006761ce4de4	3 hrs 5 mins ago	0x92a3d57a912488665946646c123b0c5d3722ea8c	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	501.793375	Litentry (LIT)
0xfbd778310d2b08c183a564de912355cf6c923b27e2fa4bd5cbc17be0ae101fc7	3 hrs 6 mins ago	0x92a3d57a912488665946646c123b0c5d3722ea8c	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	413.79544305	StaFi (FIS)
0x75f905d63f8725364e6feb94d2502e0f98b0890e4fa816a8db3dc838d7d92f08	3 hrs 9 mins ago	0x33a54fd3dbe912d7725962d216970ec1189321c0	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	15,136.99488655	LooksRare To... (LOOKS)
0x5f4ec7cd2719489b1153f84c72ffca0d4e152945d4848c8f0a2eabc61f8c257b	3 hrs 10 mins ago	0x33a54fd3dbe912d7725962d216970ec1189321c0	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	7.92	Staked Aave (stkAAV...)
0x1b76784ae516a45d3cd0d73b81e5235b9c32aedc7f84f8290700887050e8810a	3 hrs 12 mins ago	0x33a54fd3dbe912d7725962d216970ec1189321c0	 IN 	0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82	0.22316481	Wrapped Ethe... (WETH)

All those sender is sending all assets to 0x89e7d7b622fe0dcc53c42cee12a9ebdc9fa29c82

I been research possibility:

I mean theres tons of addresses out there so its like how could you not hit one

Because there are this many possible valid 12 word seeds:
340,282,366,920,938,463,463,374,607,431,768,211,456

Like I said I'm not an expert, just want to share. make this thread as archive in case there solved or new case found.

I think like a case like someone guessing the private key with what he already has, I once ruffled a private key and got a wallet that contains meme coins that are not in Exchanges, but it looks that the wallet has not been used for a long time.

[Lizzylove1]

Mnemonic phrase has always been saved, it's the way you handle your wallets that determines the security and safety. Some persons store their recovery phrase on emails, google drive, notepad and other online security storages. This should be discontinued and never to be tolerated for any reason. I understand some persons have been caught unaware in this era of web3 and Defi movement due to phishing links compromising their wallets, therefore it's important to practice proper wallet management and deploy hardware wallet for bigger fund.

[Victorik]

The wallet was hacked, but I don't think it has anything to do with his mnemonic phrase, except someone else had access to it. Otherwise, I believe this hacking may be attributed to interaction with a malicious smart contract.

[Kelvinid]

Mnemonic are safe but your computer is not so most probably your friend pc got compromised and that’s why he get hacked. Hackers can’t get your money unless you publicly post the details of your wallet or you downloaded a malware that can get your informations easily. That’s too back to get hacked, and a costly lesson to be learned. Well, better to secure your wallet and make it your outmost priority.

I'd see this stance happens mostly to those who lose their private keys or Mnemonic. It is very understandable that once our PC has been attacked by malware, it was easy for the hackers to control on it. Things that we need to keep in mind - there is no safety assurance storing our password/keys in the computer as it was advisable to right it dows in a paper for more safety. Definitely, there is no problem with the Mnemonic, in fact, many people are using this. The problem is that the one who manage to keep those stuff. Usually we neglect to do it.

[Maidak]

There might be some part of the story that we didn't know since OP just conclude right away that it's because of mnemonics being not safe. OP should look at all sides of the case starting from the hardware/devices that were used or might be his friend did some unintentional action that is not aware of.

Technically, mnemonics are safe and can't be breached that just easy. Although I'm not really aware of this Coin98 wallet and I'm confused about how on earth your friend ended up with a wallet that I can't even consider as popular or reputable.

I experienced it, it is a multi-chain wallet like trustwallet and has all versions for browser and phone. My experience is that it is quite slow and quite difficult to use if you are newbie, but in terms of security, I have no problem with it as I have used it to store some assets worth more than $1k. I think it's not the wallet provider's fault but maybe the OP's own fault, maybe he connected to a phishing site or his computer has a virus...In this case, he can try contacting coin98 support directly to get it resolved instead of asking here.

[erep]

Your friend must be careful in using it. instead when we login in metamask or the dappps application, if he is an airdrop player or the like, try to pay attention to the incoming token, there is a possibility that it is a dusting token. This is what makes your friends' wallets likely to be broken by hackers, they are very clever, even a small gap can be an opportunity for them.

I suggest that you use a new metamask account or dapps app in a new browser, because any connection wallets in third party apps will be very vulnerable to wallet hacking, so we have to disconnect every dapps after we use them, so any potential tokens that have landed in the wallet are recommended to send it to another address for the wallet holder, if we follow the advice above then we can anticipate losing assets in the wallet.

[abel1337]

Mnemonic phrase is hackable is hackable, Though there are several types of way to hack that like phishing, hacker having access to your computer and many more way to hack that secret phrase of yours but I will personally use and recommend it since I haven't experienced being hacked yet. I think it is safer compared on using custodial wallets that is much more prone to hacking or being removed to access to your own funds. Everything is hackable, It will depends on how you will keep and manage the security of your own assets.

[Oneandpure]

I suggest that you use a new metamask account or dapps app in a new browser, because any connection wallets in third party apps will be very vulnerable to wallet hacking, so we have to disconnect every dapps after we use them, so any potential tokens that have landed in the wallet are recommended to send it to another address for the wallet holder, if we follow the advice above then we can anticipate losing assets in the wallet.

Disconnect only still not enough secure wallet connecting with several dapp exchange exactly with new dapp browser, need to revoke all connection if want secure wallet assets or metamask account. Used new metamask wallet is good option but need to refill fees every time make transaction. Better with disconnect and revoke all connecting after use dapp exchange with metamask connecting. I used beefy.finance for revoke all connecting with dapp exchange, as soon possible after transaction or swap make revoke connecting without have space or time delay could be chance for wallet hack.

[Bitstar_coin]

This is why it is advisable to use a different wallet for Airdrops if you are the type that participates in airdrops however, I too don't think Mnemonic is that easy to break if you did not place them carelessly. Safeguarding your login information can not be overemphasized and connecting your wallet to every site is not advisable too, I would normally write down all my Info in different Dairies and have soft copies of them too, and these devices I never connect to the internet.

Very true, till now many crypto users don't know the great danger of using the main wallet which holds huge amounts of funds to participate in airdrops, especially those that will require the user to connect to the website.  It is through this process and other ways that a hacker can have access to one's wallet. It is very important to take note of this and other possible ways like always disconnecting your wallet completely from any site you connect it to, ever since I read about wallet disconnection, I try to make it a point of duty to do so.
Mnemonic is very safe the way it was used is the problem.

[goaldigger]

I think Mnemonic are safe because many wallet like metamask, Trustwallet we create a new wallet so we use mnemonic through we create so mnemonic are safe way but some time we save mnemonic in that file are email etc which are hack easily then hackers easily open over wallet so secure your system other than mnemonic phrase are safe.

It’s safe not until you expose those data into hackers or your pc might got the virus which collects personal data. I’ve been dealing with this wallet for years already and so far, I have no problem with some of my token. I support the other claims here that OP your friend might already exposed to hackers and probably downloaded a file from unknown source or it can also be an inside job. I have my crypto friends as well but I’m not letting them to touch my PC without my permission, this is to be more safe.

[TimeTeller]

I think Mnemonic are safe because many wallet like metamask, Trustwallet we create a new wallet so we use mnemonic through we create so mnemonic are safe way but some time we save mnemonic in that file are email etc which are hack easily then hackers easily open over wallet so secure your system other than mnemonic phrase are safe.

It’s safe not until you expose those data into hackers or your pc might got the virus which collects personal data. I’ve been dealing with this wallet for years already and so far, I have no problem with some of my token. I support the other claims here that OP your friend might already exposed to hackers and probably downloaded a file from unknown source or it can also be an inside job. I have my crypto friends as well but I’m not letting them to touch my PC without my permission, this is to be more safe.

As hacking softwares or tools are getting sophisticated, your computer will not be safe from hacking or phishing anymore.
These days, we are mostly online and we don't know if we visited the site as potential source of malware or virus.
As much as possible, separate the computer that you are having your funds with, and if possible, not connect it the net all the time.
You can't trace where they will look for vulnerabilities. So what you can do is you need to take care of your own online credentials.
As well as limit your exposure to potential attacks. These hackers don't care who they are dealing with, so long they are exhausting funds.

[fuguebtc]

I suggest that you use a new metamask account or dapps app in a new browser, because any connection wallets in third party apps will be very vulnerable to wallet hacking, so we have to disconnect every dapps after we use them, so any potential tokens that have landed in the wallet are recommended to send it to another address for the wallet holder, if we follow the advice above then we can anticipate losing assets in the wallet.

Disconnect only still not enough secure wallet connecting with several dapp exchange exactly with new dapp browser, need to revoke all connection if want secure wallet assets or metamask account. Used new metamask wallet is good option but need to refill fees every time make transaction. Better with disconnect and revoke all connecting after use dapp exchange with metamask connecting. I used beefy.finance for revoke all connecting with dapp exchange, as soon possible after transaction or swap make revoke connecting without have space or time delay could be chance for wallet hack.

In this case, I think OP's friend didn't revoke the previous permissions he granted to an untrusted DEX or dapps. When we connect to dapp or DEX it will always ask us to accept permission and many people didn't notice but clicked full permission button this means they have full access to our wallet. This is a common error and not many people know, after finishing the transaction, we always have to disconnect and revoke all the permissions that we have previously granted.