In a recently published report on the state of the Internet security, Akami Research  notes that they detected an average of 115 million credential stuffing attacks against their clients each day in 2018.

Credential Stuffing is, according to OWASP: “the automated injection of breached username/password pairs in order to fraudulently gain access to user accounts. This is a subset of the brute force attack category: large numbers of spilled credentials are automatically entered into websites until they are potentially matched to an existing account, which the attacker can then hijack for their own purposes.”

Credential Stuffing is not attempting to guess the password for a certain user account, it is simply trying the known (stolen or spilled) username / password combinations from “website 1” against the login page of “website 2”.  Since many sites use an email address as a username and many users reuse the same password on many sites – credential stuffing attacks have a worthwhile chance of success.

Often driven by Botnets which are geographically diverse, credential stuffing attacks are not mitigated by the usual velocity checks designed to prevent attacks against an individual account by trying multiple passwords.  This makes it hard for individual servers to defend against as the traffic looks much like valid user login attempts.  This is why infrastructure providers such as Akami are able to identify and attempt to mitigate and block the attacks because they can discern the common traffic patterns of the attackers across their infrastructure as they target multiple clients servers.

Akami reports a marked rise in the use of specially developed bots which target online retail stores using credential stuffing and then after a successful login complete an automated purchase. The criminals then resell the purchased goods to generate funds.  Known as All-In-One or AIO bots, these targeted malware packages are readily available for sale online and even offer versions customised to attack single retailers of high end goods and clothing.

The researchers noted that some of the attacks against high end retailers appear to be conducted purely as a means for validating the credentials. In this scenario the thinking is: if the spilled credentials are found to work against a high end retailer it is more likely the owner of the credentials has reused the same credentials in other places as well and then the credentials are tested against financial institutions.  By doing the bulk testing of the credential pairs against retailers first rather than going direct to the financial institutions, it is thought the criminals are attempting to fly under the radar assuming that online retailers have less sophisticated cyber-security measures in place than a bank would.