Posted by Kevin on May 24, 2014.
There are two functions to PR: the first is to shout the good news from the hilltops, while the second is to bury the bad. When bad news hits, PR says very little.
Bad news has hit eBay. It admitted Wednesday that it had been hacked – but it actually gives very little information. This is a mistake. It means that people will comb their words used looking for clues over what has actually happened. The result is conjecture; but what follows is the conjecture of some very clever security people.
Three things leap out from the eBay statement. The first is the repeated use of the word ‘encrypted’, with no mention of hashing for the passwords. The second is the duration of the breach – it occurred in February/March, but was only discovered a couple of weeks ago. And the third is the mention of the database – not part of, nor a geographical region, but the (whole?) database. So what can we surmise from all this?
Firstly, were the passwords encrypted or hashed? It makes a difference. The implication from the statement is that they were encrypted. Most security experts believe that this would be a mistake – passwords should be hashed and salted. In fact, Ian Pratt, co-founder of Bromium, goes so far as to suggest, “It would be rather unusual to encrypt passwords rather than hash them; it’s probably just lack of precision in the statement.”
But that’s what we said about the Adobe breach – and it turned out that the passwords were indeed encrypted rather than hashed. The opinion among the experts I talked to is fairly evenly balanced – while eBay’s semantics suggest they used encryption, many experts find it hard to believe. “This heavily implies that the passwords were not hashed,” said Chris Oakley, principle security consultant at Nettitude. “eBay’s report suggests that the passwords were encrypted rather than hashed,” added Brendan Rizzo, Technical Director EMEA for Voltage Security. Sati Bains, COO of Sestus, said, “Yes… it appears from the comment that they did [encrypt rather than hash].”
“Encryption and hashing are often confused with each other,” explains Jon French, a security analyst at AppRiver. “But from the sounds of the [eBay’s] press release, it seems they were using some sort of encryption.”
Andrey Dulkin, senior director of cyber innovation at CyberArk, is in no doubt. “Indeed, from the eBay statements we understand that the passwords were encrypted, rather than hashed. The fact that the statements repeatedly use the words ‘encrypted’ and ‘decrypted’ supports this interpretation.”
It is, of course, possible that eBay is simply not differentiating between the two processes, since most of its customers will not understand the difference. “The public understand the word ‘encrypted’ more than hashed – so encrypt is frequently used in place of hashed. But it is believed they were hashed,” suggests Guy Bunker, spokesperson for the Jericho Forum and a cyber security expert at Clearswift.
Ilia Kolochenko, founder and CEO of High-Tech Bridge (HTB), doesn’t believe we can tell from eBay’s comments. “The difference isn’t easily understood by users. Even the spokesperson might not be aware. It’s quite possible that the company simply didn’t want to introduce the complexity of describing the technicalities of hashing and salting in a brief announcement.”
What’s the difference, and why does it matter?
The primary operational difference is that encryption can be decrypted; that is the original plaintext can be retrieved from the ciphertext through the use of the encryption key. Hashed outputs cannot be mathematically returned to the original plaintext.
In practice, an entire database of passwords would be encrypted via a single encryption key. But if hashing was used, each individual password would ideally have an unknown value added to it (a ‘salt’) and the results would be separately hashed. “This salt,” explains Voltage’s Rizzo, “is a way to make sure that the hash of a particular password cannot be compared to the known hash of that same password by the attacker through the use of rainbow tables.”
This means that if an encrypted database is stolen, only one key needs to be found to unlock every password in the database.If the passwords are hashed, every single password needs to be cracked individually.
“The advantages to hashing,” Nick Piagentini, senior solutions architect at CloudPassage, told me, “are one, there is no need to manage sensitive encryption keys; two, hashing processes have less overhead to run than encryption processes; and three, there is no need to reconstruct the password data from the hash. Encryption would only be used if there was a need to get the original password back.”
Could the hackers have the encryption key?
This is the 64 million dollar question (and is only relevant if the passwords were encrypted). We don’t know, and we may never know. But it is certainly possible. There are two possibilities: it could have been cracked or it could have been stolen.
Reuters spoke to eBay spokeswoman Amanda Miller:
She said the hackers gained access to 145 million records of which they copied “a large part”. Those records contained passwords as well as email addresses, birth dates, mailing addresses and other personal information, but not financial data such as credit card numbers.
Hackers raid eBay in historic breach, access 145 million records
eBay says the database was compromised some time around late February or early March; but wasn’t discovered until about two weeks ago. What we don’t know is whether the compromise was still in active use by the hackers, what else they did during the two months they were undetected, or whether they left something unwelcome behind. Frankly, I find it hard to believe that having gained access without being discovered the hackers did not have a good look round.
(Incidentally, it is worth pointing out at this point another comment from HTB’s Kolochenko. Basically, eBay’s statement that financial details were safely stored on a separate server is pretty meaningless. “The two servers would have to communicate,” he explained. “The hackers could have installed some malware to listen to the communication between the servers, and sniffed the plaintext traveling between them.”)
So could they have found the encryption key? Opinion is divided. “This is a primary argument for using hashing over encryption for password storage,” comments Nettitude’s Oakley; “an attacker who is able to compromise the database may also be in a position to obtain the encryption key(s).” (Incidentally, if the passwords were hashed rather than encrypted, the hackers could just as likely have found the salt or salt mechanism, rendering the hashed passwords relatively easy to crack via rainbow tables.)
On the other hand, “I would hope they [eBay] didn’t ‘tape the key to the door of the safe’”, comments Trey Ford, global security strategist at Rapid7. “eBay and PayPal have solid security teams, and go through regular third-party assessments. I refuse to believe they would handle encryption key materials that poorly.”
And yet they left the users’ email addresses and other personal information unencrypted. If they were using encryption seriously, they would have used a hardware security module (HSM) to house the keys, and would have encrypted everything. “They do not seem to be very confident about their encryption system,” comments Sebastian Munoz, CEO of REALSEC, “when they are suggesting their customers to reset passwords. If efficiently encrypted, using specific certified hardware, there would be no need to reset the passwords, since protection is guaranteed. When you use a Hardware Security Module (HSM) and not a simple and insecure encryption-by-software process, there is no way that hackers can gain access to the encryption keys.”
Munoz further suspects that software based encryption was used since only the passwords were encrypted. Since software encryption impacts on performance, then cost arguments come into play.
So, given the duration of the breach and the probable lack of an HSM, it is perfectly possible that the hackers also found the encryption key – and if this is the case, they now have access to all of the greater part of 145 million passwords, along with ‘email address, physical address, phone number and date of birth’.
If they did not find the key, would they be able to crack the encryption key? Again, opinion is divided – it all depends upon what encryption algorithm was used. Older encryption algorithms might be susceptible to a ‘known plaintext’ attack (see Wikipedia for details). Getting the necessary plaintext would be no problem. The most popular passwords are remarkable consistent – so a simple analysis with something like DigiNinja’s Pipal on an existing cracked database would provide a fair sampling of plaintext.
“However,” notes Bromium’s Ian Pratt, “assuming any kind of modern encryption (e.g. AES-128) was used then a known plaintext attack should not be feasible to recover the key and hence reveal other passwords.”
“Another approach,” suggested Clearswift’s Bunker, “is to ‘inject’ known passwords (either the hash or the encrypted version) into the database. This would create the equivalent of denial of service for the individual but would allow the attacker free reign over the account.”
The problem is we simply do not know what has happened. eBay’s attempts to downplay the incident is simply leading to conjecture.
While writing this report, Rapid7’s Trey Ford noticed adverts for the sale of eBay’s stolen database beginning to appear on Pastebin. “There has now been a posting on pastebin claiming to offer ‘145 312 663 unique records’ relating to the eBay breach,” he told me by email. We don’t know if they’re genuine, “it’s possible that a criminal has just spotted an opportunity to cash in on the attack with some other credentials dump they have.”
An analysis of the sample provided is inconclusive – the records are possibly genuine but not certainly genuine. But Ford had a look at the sample:
The sample that has been shared indicates that cracking the passwords will take considerable time. This is nothing like what we saw when LinkedIn was breached and the stolen credentials were quickly cracked due to only SHA-1 hashing being used for storage. In contrast, this credentials set is using PBKDF2 (Password-Based Key Derivation Function 2) SHA-256 hashes, which means they employ a strong hash function and also intentionally make cracking them more difficult and slow by individually salting and using a high number of hash iterations. The method used can be regarded as the state-of-the-art way to store passwords on web applications. Again though, we don’t know that these are credentials taken from the eBay breach, and no details have come from eBay on how they secure passwords.
This would fit in with eBay’s apparent confidence that the passwords cannot be hacked. However, Reuters spoke to eBay about the sample, and
eBay’s [spokesperson Amanda] Miller said the information was not authentic.
U.S. states probe eBay cyber attack as customers complain
AppRiver’s Jon French also noticed the Pastebin offer. He told me by email,
I’ll be wary of anything like this until I see people saying they see their own names (or if I end up seeing mine). Eventually if the Pastebin offer is legit, someone will post the file for free somewhere or some security company that buys it will verify authenticity.
His colleague, Troy Gill, a senior security analyst at AppRiver also suggested something that serious criminals will be well aware of: “There is always the remote possibility that this is a honey pot set by authorities to lure in would be buyers.”
eBay is taking the standard route for crisis management: say nothing. This is hugely disrespectful to its customers, who need and have a right to know everything possible. But eBay is also making a mistake in trying to downplay the effect of the stolen data. It says it has “no evidence of the compromise resulting in unauthorized activity for eBay users, and no evidence of any unauthorized access to financial or credit card information.” This is meant to make its customers feel better – the danger is that it might.
What eBay isn’t saying is that the unencrypted personal data also stolen (email address, physical address, phone number and date of birth) is a phisher’s wet dream. Armed with that information criminals will be able to concoct very compelling emails and cold call telephone calls. This is likely to happen on a vast scale and very soon. eBay might feel confidant about its own business, but the data it has lost puts millions of individuals and other companies in danger.
“When companies like eBay keep silent about the details,” commented High-Tech Bridge’s Kolochenko, “I would tend to expect the worst.” It is perhaps worth remembering the Adobe incident, which started off with a breach of a couple of million and slowly escalated into one of the worst breaches in history.Submitted in: News, News_hacks |