Protect Your Data From CSV & DDE Attacks
By Tom Seest
At BestCybersecurityNews, we help entrepreneurs, solopreneurs, young learners, and seniors learn more about cybersecurity.
Many web applications provide functionality to export data onto spreadsheet files, which often contain sensitive information that must be handled carefully and safely.
Unfortunately, security controls for these types of files often leave them open to attack, CSV injection attacks (commonly referred to as formula injection) being one such example.
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CSV Injection is an attack that occurs when web applications do not properly sanitize their exported CSV data, enabling attackers to craft malicious formulae that will execute when users open up the file on their computers – potentially enabling remote code execution or accessing sensitive information from one machine.
This attack takes advantage of the fact that many spreadsheet programs, including Excel, look for certain characters to indicate when formulae are present and then execute programs when these characters are encountered in files. This variation on more familiar macro attacks found in spam/scan email attachments or ransomware infections is a potential route into financial gain for an attacker.
By exploiting this feature and the user’s tendency to disregard security warnings in downloaded spreadsheet files, an attacker can convince their victims to download an infected file containing malicious formulae that execute when opened – leading to remote processes (usually designed to install malware or access data) being initiated from them.
This is a common issue when web applications export data to CSV files and can be prevented using various means, including regular expressions, blacklisting certain characters, and escaping other characters from being included in sanitized data export. Sanitization should always precede export of any kind.
Another mitigation technique involves creating a custom CSV exporter that strips out text beginning with equal signs, as this may help stop some of the more serious attacks but may not always be sufficient to stop all.
There are various mitigation techniques that can help protect against this attack, such as encoding data before writing it to a CSV file and warning users before downloading one. You could also use the setForceFieldEnclosure function of your exporter config (setForceFieldEnclosure) to stop certain characters that might be seen as formulae when exported – for instance, plus (+), minus (-), or at (@) characters – being added by default when CSV exporting, making it much harder for an attacker to create malicious CSV files which could result in malicious remote execution or data breach.
Attackers also leverage Excel’s Dynamic Data Exchange (DDE). DDE allows applications like Word or spreadsheet programs such as Excel to communicate with other programs through Windows API in order to retrieve or update data in files; it is especially helpful when an attack requires accessing different data locations.
DDE attacks involve injecting malicious payload into a cell before exporting it to the victim’s computer. Once there, this malicious payload gets interpreted by host applications as a macro, which then executes various commands ranging from downloading a document or file that contains malware to installing code onto their machine.
This technique is commonly utilized during phishing campaigns and red team assessments to gain remote code execution on their target system, making it one of the most frequently seen attacks today.
Criminals recently deployed a novel tactic for disseminating malware: using text-based CSV files with an exploited exploit for Microsoft Office products as CSV files to install exploits via an old Dynamic Data Exchange function called “Dynamic Data Exchange.” The exploit exploits a vulnerability within that function in order to download and execute remote executable files.
Microsoft recently issued an update to Word that disables DDE; however, this does not preclude such attacks from succeeding. Furthermore, some older versions of Excel still allow DDE activation.
DDE Injection attacks can be avoided by creating a simple rule in your web application that validates all untrusted input against an acceptable list of characters such as equals (=), plus (+), and minus signs (-). This type of validation can easily be implemented and should be recommended for environments producing CSV files.
Recently, a variant of the CSV DDE injection exploit has emerged in phishing attacks and spam emails, using two obfuscations and variations designed to bypass antivirus software. This serves as a stark reminder that threats are constantly evolving – it’s crucial that defenses stay vigilant against all possible threat vectors.
Social engineering attacks pose a grave danger to cybersecurity, exploiting natural human emotions like fear and curiosity to carry out schemes and gain sensitive data from users. Such attacks can take the form of email phishing scams, text messages, peer-to-peer sites, malicious websites, and even phone calls; criminals then use this data to access accounts, cause users to believe they’re being attacked, and even infect systems with malware.
One infamous example of social engineering attacks occurred with the 2011 data breach at cybersecurity company RSA. Attackers sent two phishing emails daily targeting small groups of employees at RSA; one contained an Excel file which, when opened, installed malware onto victims’ systems, which, in turn, provided attackers access to RSA’s network and their SecurID passwords.
Social engineering attacks can be prevented with proper security measures in place, including multifactor authentication. By making it more difficult for hackers to acquire user credentials, multifactor authentication acts as an additional layer of protection against social engineering attacks by forcing hackers to crack an extra factor (usually an app code or biometric data) before being granted entry.
One effective strategy to protect against social engineering attacks is educating your employees about the tactics that bad actors employ. Although the days of Nigerian princes may have passed, it remains important to remind employees to always remain suspicious about emails or digital media that seem too good to be true.
Finally, conduct penetration tests and security simulations regularly to stay ahead of new attacks. Such simulations will equip your team with tools for quickly detecting and mitigating vulnerabilities before hackers exploit them. A comprehensive penetration test can also identify any weaknesses in your organization’s security stack – offering a roadmap on how to improve them. Deepak is the CTO and co-founder of LoginRadius, a fast-growing Customer Identity Management provider. He is passionate about innovating the platform while playing football – both qualities he has displayed throughout his career.
CSV Injection Attacks occur when web applications permit users to export data from their accounts directly into CSV files without validating or checking for accuracy, which opens up opportunities for attackers to inject malicious formulas that will then execute when opened by victims, potentially leading to devastating results such as data and system compromise. However, this attack vector may be mitigated through properly coding user input that prevents these maliciously injected formulas from running as expected, thus mitigating this attack vector.
CSV injection attacks are one of the more sophisticated types of DDE injection attacks and are commonly known as formula injection attacks. These exploit spreadsheet software such as Microsoft Excel or LibreOffice Calc to inject formulas onto victims’ machines that may range from links to harmful programs or even command executions.
Developers can protect against these attacks by not accepting input that could potentially be misinterpreted as formulae. To do this, developers should usually reject characters beginning with +, -, =, or @ (which are known as spreadsheet meta characters) when accepting input for cells; alternatively, any necessary characters could be preceded with single quotes to ensure their use does not qualify as formulae or be considered part of formulas; this practice is known as neutralizing characters – one of the primary strategies against CSV injection attacks.
An individual can also protect themselves from these kinds of attacks by employing a firewall and only clicking links in files sent from unknown sources; however, even this won’t always provide total protection; attackers could use social engineering techniques to convince victims to click on harmful links in these files.
CSV injection attacks represent a serious security threat that should be mitigated as soon as possible. They are difficult to detect, exploiting the trust relationship between victims and email providers, and can have disastrous repercussions if victims remain unaware that their information has been compromised. By employing appropriate mitigation and awareness strategies, these attacks can be prevented in advance.
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