Defending Against DDoS and Digital Financial Fraud
The tools of the cybercrime trade continue to evolve and proliferate in a perpetual arms race of attacker vs. defender
Aug. 8, 2013 10:00 AM
The reemergence of the Dirt Jumper botnet in association with fraudulent wire transfer and ACH transactions continues to highlight one simple truth: cybercriminals are all about money, whether it is generated directly via fraud or via access to information.
Dirt Jumper came into the spotlight in 2011 as a spinoff of the Russkill botnet. Since its emergence, the Dirt Jumper family of bots (botnet) has been implicated in dozens of politically and financially motivated attacks against organization of all types, sometimes demanding a ransom, at other times coinciding with fraudulent activity such as ACH or wire transfers. Over time, botnets such as Dirt Jumper have evolved as a business in and of themselves, giving anyone with a motive - let alone a cybercriminal - an opportunity to carry out a DDoS attack against an organization, sometimes for as low as $50 per hour, complete with technical support. Organized crime has fully metastasized into the digital realm.
A distributed denial of service (DDoS) attack perpetrated in concert with a fraud event not only reduces an organization's situational awareness by drawing away resources, the attack also serves to boost the financial damage to the target organization. While recent events such as "OP-USA" denial of service and web application attacks have the stated purpose of protest from hacktivist groups, they may simply be a ploy to direct resources away from the real, more damaging attack against financial or other information assets. The real cost of a combined DDoS attack and transfer fraud event is rarely fully accounted for when one considers customer impact, remediation man hours, and loss of good will/reputation. Also note that consumer protections for banking fraud often don't apply to businesses, as such organizations must be extra vigilant to ensure they don't fall victim.
Limiting potential losses as the result of a DDoS attack is one element of risk mitigation that allows an organization to maintain situational awareness during an attack. However, handling DDoS attacks is secondary to comprehensive data security, operational security, and accounting practices. Through better security policies, an organization can substantially increase the investment of resources required by cybercriminals to successfully carry out fraudulent ACH or wire transfer schemes, thereby making it more likely fraudsters will seek easier targets.
Here are some best practices and recommendations that will decrease an organization's exposure to wire transfer or ACH fraud and reduce the impact of a diversionary DDoS attack.
- Mitigate DDoS attacks:
- Implement an on-premises or "Cloud/ISP" DDoS mitigation solution. These solutions can be passive, active, or a combination thereof. On-premises DDoS mitigation solutions typically provide finer granularity and instantaneous response while "Cloud" or ISP solutions can provide full protection from bandwidth saturation attacks at the expense or granularity and response time.
- Consider implementing ISP and/or on-demand CDN traffic filtering for Internet facing applications, including employee remote access.
- Deploy a Web application firewall (WAF). Most stateful inspection firewalls will be entirely ineffective against an application layer DDoS attack. A WAF will also serve the dual purpose of hardening the application. In addition, the application delivery controller (ADC) will often have features for full spectrum application protection far beyond the capabilities of a legacy firewall.
- Consider implementing traffic filtering based on IP geo-location. Botnets are usually globally distributed, and individuals who control them rarely take the time to ensure they are all in one country. You can therefore reduce the scope of a DDoS attack by automatically filtering hosts that do not reside in areas where you do business.
- Ensure applications are protected on the internal side of the network as well. Attackers have figured out that enterprise perimeters are becoming more difficult to effectively attack and will seek to these bypass defenses by using internal hosts to launch their attacks.
- Improve or implement proper data and operational security procedures:
- Limit online banking and financial transactions to assets owned by the organization solely dedicated for that purpose. These assets should be isolated on the network, monitored closely, and functionally limited only for the necessary transactions. These hosts should be offline when not in use, if possible.
- Avoid accessing online banking applications from a public computer or public network.
- Implement multifactor or out-of-band authentication for banking services and applications.
- Ensure credentials for financial transactions are unrelated to other credentials (that is, PC logins, e-mail addresses, etc.). In addition, authentication credentials for employees or agents involved in financial transactions should meet stricter standards such as longer passwords and shorter validity periods.
- Implement solid computer security practices throughout the organization. These include but are not limited to anti-virus/malware/host IPS, aggressive patch management, software whitelisting, data encryption, and restrictions on administrative privileges.
- Educate users involved in financial transactions to recognize social engineering attacks via e-mail, phone, social media, or even in person, whether for business or personal interactions.
- Combat insider fraud with two-person authentication and/or authorization: With two-person control to authorize significant transactions, an organization can substantially decrease the risk of insider ACH or wire transfer fraud; as such, an act would require collusion.
- If you are a small business conducting banking with the same institution, maintain separate credentials for your business and personal accounts.
- Consider implementing URL whitelisting: Only allow communications to URLs relevant to your business. This practice will make it significantly more difficult for an attacker to execute a compromise and/or maintain a bridgehead in case of a compromised asset.
- Maintain good accounting practices:
- Limit ACH debits to a specific account.
- Implement Positive Pay on all accounts with ACH, potentially with payee verification.
- Reconcile all accounts daily and return unauthorized transactions.
- Add "Post No Checks" restrictions to deposit accounts.
- Subscribe to third-party fraud control services.
- Implement procurement cards with transaction filters.
The tools of the cybercrime trade continue to evolve and proliferate in a perpetual arms race of attacker vs. defender. These recommendations are by no means an exhaustive list of steps an organization can take to combat fraud and an associated DDoS attack. However, these recommendations combined, applied, and incrementally enhanced over time to the unique needs of your business will reduce the risk that your organization will fall victim to organized cybercrime.