The miscreants who have poisoned more than half a million web pages aren't the only attackers thinking big. People behind a botnet known as Asprox have recently rejiggered their army to infect websites in a similar fashion.
Asprox zombies have recently been blessed with a tool that sniffs out potentially vulnerable sites running Microsoft's Active Server Pages and then tries to commandeer them using SQL injections. When infections are successful, the pages then redirect visitors to websites that silently install a malware cocktail that includes the Asprox malware. The vicious cycle gives the scheme worm-like capabilities.
"Because the tool is distributed by the botnet, it may appear to be worm-like in its operation, which may lead to conflicting reports in the media and blogs about the true nature of the attack," Joe Stewart, the SecureWorks researcher who discovered the attack, wrote in a report. "However, the SQL attack tool does not spread on its own, it relies on the Asprox botnet in order to propagate to new hosts."
SQL injection attacks have emerged as the flavor of the month for criminals looking for ways to spread their malware. The seemingly endless supply of servers that haven't been properly locked down by administrators makes them easy to carry out. Once infected, legitimate websites, some of them operated by the Department of Homeland Security and other high-profile organizations, become a means for transmitting malware to thousands of end users' PCs.
At time of writing, only four of the top 32 anti-virus products detected the SQL injection tool, according to this analysis from VirusTotal.
Unlike the earlier SQL injections, which appear to be carried out by Chinese attackers, the Asprox variant is most likely being spread by people from Eastern Europe, Stewart said. It's unclear how the tools the latter group is using were acquired. They may have bought or stolen them, or developed them from scratch.
It bears repeating that most of the recent SQL attacks haven't exploited vulnerabilities in ASP or other languages that access SQL databases. The fault almost always lies with web app developers who fail to sanitize user input before sending it to the database.
The main purpose of Asprox is to send spam. Prior to the SQL attack, it had about 15,000 infected machines. ®