The Russian-language Darknet site sells a program that allows you to distribute spam messages bypassing traffic and email protection tools. The program uses a function in the IMAP protocol.
A new tool for spammers is actively being sold on the Darknet, which allows you to bypass the standard protection of e-mail accounts. By exploiting a feature in the Internet Message Access Protocol (IMAP), attackers upload the messages they need directly into the mailboxes of victims.
To trigger the attack, it is necessary that the attackers already have access to the victim’s account. The Email Appender malware has been actively promoted on Russian-language hacker forums since the fall of 2020.
The author offers to use the program through a subscription — $50 for one day, $300 for a week or $1000 per month. This is very expensive, but judging by the latest campaigns, the demand for this service is very high.
Experts of the information security company Vade Security indicate that companies in Italy, France, Denmark and the United States have already been subjected to full-scale attacks by spammers using Email Appender. One of the affected organizations claims that it received 300 thousand spam messages in one day and was forced to spend very substantial resources to disable compromised accounts or change usernames and passwords.
Databases of usernames and passwords to mail are actively sold out on hacker forums. According to Gemini Advisory, an attacker can upload such a database to Email Appender, after which the program will try to connect to accounts that match pairs of usernames and passwords via IMAP. Next, it remains to use the IMAP function, which allows hackers to upload ready-made mail messages to the mailbox.
“There are a number of ways to block such spam campaigns, but the main one is to regularly change passwords and not use the same combination (or similar to it) more than once,” said Alexey Vodiasov, technical Director of the company SEC Consult Services.
In addition, according to Vodiasov, two-factor authorization is effective, so that even a compromised account cannot be connected without attracting the attention of its rightful owner.
The expert added that it is also possible to enable notifications of cases of logging into an account from unusual IP addresses. Mail systems are quite capable of doing this.