The blog post details a sophisticated, low-and-slow password spray attack targeting Microsoft 365 accounts. Instead of rapid, easily detected attempts, the attackers used a large botnet to try a small number of common passwords against a massive list of usernames, cycling through different IP addresses and spreading attempts over weeks or months. This approach evaded typical rate-limiting security measures. The attack was discovered through unusual authentication patterns showing a high failure rate with specific common passwords across many accounts. The post emphasizes the importance of strong, unique passwords, multi-factor authentication, and robust monitoring to detect such subtle attacks.
This blog post from Petra Security details a sophisticated, low-and-slow password spraying attack they observed targeting one of their clients, a large organization with thousands of Microsoft 365 user accounts. Unlike typical brute-force attacks that try many passwords against a single account, or rapid password spraying that tries a small number of common passwords against many accounts, this attack was uniquely stealthy and persistent. It employed a combination of techniques designed to evade detection by traditional security monitoring tools.
The attackers distributed their attempts over an extended period, targeting only a handful of user accounts each day. This minimized the likelihood of triggering account lockout thresholds or alerting security information and event management (SIEM) systems. Furthermore, they cycled through a diverse list of nearly 20,000 unique passwords, further reducing the chances of raising red flags. This meticulous approach allowed them to remain under the radar for an impressive nine months.
Petra Security uncovered the attack through their unique User Entity Behavior Analytics (UEBA) technology. This system analyzes user behavior patterns, including login attempts, and identifies anomalies that deviate from established baselines. In this case, the consistent, low-volume login failures across multiple accounts over time triggered an alert, despite the individual attempts appearing innocuous in isolation.
The investigation revealed that the attackers were leveraging residential IP addresses, likely belonging to compromised home routers or IoT devices within a botnet. This tactic further obscured their activities by making the attacks appear to originate from legitimate sources, adding another layer of complexity to detection.
The post highlights the increasing sophistication of modern cyberattacks and the inadequacy of traditional security measures in addressing these evolving threats. It emphasizes the importance of adopting advanced behavioral analytics and UEBA solutions to detect subtle, long-term attacks that can bypass conventional security defenses. By monitoring user behavior and identifying deviations from normal activity, organizations can proactively uncover these stealthy attacks and mitigate potential damage before significant breaches occur. The post concludes by recommending organizations prioritize implementing robust multi-factor authentication (MFA) as a crucial defensive measure against password-based attacks, regardless of their sophistication.
Summary of Comments ( 15 )
https://news.ycombinator.com/item?id=43512944
HN users discussed the practicality of the password spraying attack described in the article, questioning its effectiveness against organizations with robust security measures like rate limiting, account lockouts, and multi-factor authentication. Some commenters highlighted the importance of educating users about password hygiene and the need for strong, unique passwords. Others pointed out that the attack's "slow and steady" nature, while evasive, could be detected through careful log analysis and anomaly detection systems. The discussion also touched on the ethical implications of penetration testing and the responsibility of security researchers to disclose vulnerabilities responsibly. Several users shared personal anecdotes about encountering similar attacks and the challenges in mitigating them. Finally, some commenters expressed skepticism about the novelty of the attack, suggesting that it was a well-known technique and not a groundbreaking discovery.
The Hacker News post titled "Unmasking a slow and steady password spray attack" (linking to a Petra Security Substack article) generated a moderate number of comments, primarily focusing on the technical aspects and implications of the described attack.
Several commenters discussed the effectiveness and practicality of the described attack method. Some expressed skepticism about its widespread applicability, highlighting that the specific vulnerability exploited (allowing unlimited login attempts without lockout) is becoming increasingly rare due to improved security practices. They pointed out that many modern systems implement robust rate-limiting and account lockout mechanisms, making such slow and steady password spraying significantly less effective.
Others acknowledged the potential danger, particularly in environments where security practices are less mature. They noted that legacy systems or organizations with inadequate security configurations could still be vulnerable to this type of attack. There was some debate around the trade-offs between security and usability, with some suggesting that overly aggressive lockout policies can negatively impact legitimate users.
A few commenters delved into the technical details of the attack, discussing methods for detection and mitigation. They mentioned techniques like analyzing login logs for suspicious patterns, implementing multi-factor authentication, and using honeypot accounts to trap attackers. The use of threat intelligence feeds to identify commonly used passwords and block them proactively was also suggested.
Some comments focused on the attacker's persistence and methodology. The slow and steady nature of the attack, designed to evade detection, was highlighted as a key characteristic. The discussion also touched upon the resources and infrastructure required by the attackers to execute such campaigns, suggesting that they might be more sophisticated than initially assumed.
Finally, there was a brief discussion about the broader implications of this type of attack, including the potential damage to reputation and financial losses for affected organizations. The importance of proactive security measures and ongoing vigilance was emphasized as a key takeaway.