Indictments filed against five persons charged in a massive international hacking scheme indicate that SQL injection vulnerabilities continue to be a huge security Achilles heel for large IT operations.

The residents of Russia and Ukraine were indicted Thursday in connection with the theft of more than 160 million credit card numbers and other financial data from a virtual Who's Who of big business, including NASDAQ, JCP, Carrefour, Discover Bank, Hannaford, Heartland and Dow Jones.

The indictments allege that the victims lost some $300 million over a seven-year period between 2005 and 2012.

In a statement, Paul Fishman, U.S. Attorney for the District of New Jersey described the attacks as "cutting edge" and called the work a threat to the U.S. economy and national security.

The indictment also suggest that the hackers, in most cases, did not employ particularly sophisticated methods to gain initial entry into the corporate networks. The papers show that in most cases, the breach was made via SQL injection flaws -- a threat that has been thoroughly documented and understood for well over than a decade.

The NASDAQ network, for instance, was initially attacked via a SQL injection vulnerability on an online password reminder page. The flaw let hackers access the network without authorization to get a foothold that eventually let them gain full administrative control.

Similarly, initial unauthorized access to corporate networks at Heartland, JC Penney, Wet Seal, Visa Jordan and Diners Singapore came as a result of SQL coding errors. In each instance, the attackers rapidly escalated their privileges on the network to install malware and backdoors for stealing credit card and other data.

Via SQL injection attacks, hackers take advantage of poorly coded Web application software to install malicious code in a company's systems and network. The vulnerability exists when a Web application fails to properly filter or validate data entered by a user -- such as when ordering something online or when resetting a password.

An attacker can take advantage of input validation errors to send malformed SQL queries to the underlying database letting them break into it, plant malicious code and/or access other systems on the network.

SQL injection flaws are relatively simple to fix, once found. The challenge for IT personnel is knowing where to look for them. There are hundreds of places in large Web applications where users can input data, each of which can provide a SQL injection opportunity.

Hackers have taken advantage of SQL injection flaws for years because they can be exploited with relative ease. In recent years, SQL injection attacks have consistently ranked as one of the most popular methods for hackers to break into networks.

Security experts and organizations like the Payment Card Industry Security Council have long urged companies to thoroughly scan Web applications for such flaws. They suggest using Web application firewalls to mitigate the threat.

The PCI council mandates that companies either do a complete source code analysis to weed out such flaws or use a Web application firewall.

Even so, many companies fail to fully implement measures that can mitigate SQL injection threats, said Avivah Litan, an analyst with Gartner. "SQL injection attacks succeed because companies aren't protecting themselves well enough against them," she said.

Though companies understand the need for application code reviews and to maintain application firewalls, many neglect the task due to resource issues, Litan said.

"[Companies] just don't do it well enough because they are overwhelmed. They don't have the money or the resources," needed to address SQL issues, she said. "It really is about budget prioritization and organizational silos."

Jeremiah Grossman, founder and chief technology officer of Web application security specialist WhiteHat Security, said that software development resources are completely maxed out in many companies.

"Your coders have to push new features to customers that will drive future revenue. If they slow down, or work on anything else, like fixing vulnerabilities in their code, there is a certain monetary sacrifice. There simply isn't enough time or resources to do everything," Grossman said.

Therefore, he said. "If you are after data, as these bad guys [were], then SQL injection is the best and fastest way to breach the database. There is nothing technical about SQL injection that we don't know. We know what it is, we know how to fix it, we know how to prevent it. The central issue is the scale of the problem and development resource constraints."

Jaikumar Vijayan covers data security and privacy issues, financial services security and e-voting for Computerworld. Follow Jaikumar on Twitter at @jaivijayan, or subscribe to Jaikumar's RSS feed . His email address is jvijayan@computerworld.com.