The very authentication process designed to protect enterprise cloud environments is being weaponized in a sophisticated new attack that slips past even the most robust digital defenses. Known as “ConsentFix,” this technique exploits user trust and the legitimate mechanics of Microsoft Entra, turning a standard login flow into a gateway for attackers. The ingenuity of this threat lies not in breaking code but in manipulating a trusted system from the inside, presenting a formidable challenge to security teams who rely on conventional alerts for breach detection. This development forces a critical reevaluation of identity security, highlighting that a system’s greatest strength can also be its most exploitable vulnerability.
When Trusted Systems Turn Against You
At the heart of modern security architecture lies the principle of trust in verified authentication systems. Users and administrators alike depend on familiar login prompts and multi-factor authentication challenges as reliable gatekeepers to sensitive data and critical infrastructure. The ConsentFix attack subverts this fundamental trust by co-opting the legitimate OAuth 2.0 authorization flow. Instead of brute-forcing passwords or exploiting a software bug, it tricks the system into willingly handing over a powerful authorization code. This method’s effectiveness is rooted in its subtlety. Because the initial stages of the attack leverage Microsoft’s own authentication infrastructure, they appear completely legitimate to both the end-user and many automated security tools. The victim interacts with a genuine Microsoft login page, satisfies all security requirements, and completes a process they have likely performed countless times. It is this familiarity that becomes the attacker’s most powerful tool, lulling the user into a false sense of security right before the critical data is exfiltrated.
The New Frontline of Cloud Identity
Microsoft Entra ID stands as the central nervous system for identity and access management in countless organizations, governing access to everything from Microsoft 365 to critical Azure services. Its ubiquitous presence makes it an incredibly high-value target for threat actors. Compromising a single Entra ID account can provide an attacker with the keys to the kingdom, making it the new frontline in the battle for enterprise security. This centralization of identity, while efficient, also creates a single, highly attractive point of failure.
In parallel, phishing attacks have evolved far beyond simple credential harvesting. Modern campaigns are meticulously crafted to mimic legitimate corporate communications and identity workflows, specifically targeting identity providers like Entra ID. Attackers understand that the inherent trust users place in familiar login prompts is a significant vulnerability. By initiating a legitimate, Microsoft-hosted authentication sequence, they bypass the user’s initial skepticism, as all the visual cues and security prompts appear authentic and trustworthy.
Deconstructing the ConsentFix Attack
The attack chain begins with a carefully crafted lure: a malicious Microsoft Entra login URL. This link, typically delivered via a phishing email, is designed to request access to high-privilege applications such as the Azure CLI and Azure Resource Manager. When a victim clicks the link, they initiate what appears to be a standard OAuth 2.0 authorization code grant flow. They are presented with a legitimate Microsoft sign-in page, where they enter their credentials and complete any multi-factor authentication prompts.
The critical flaw is exploited in the final step of this otherwise legitimate process. The attacker configures the malicious application to redirect the user’s browser to a non-existent localhost address after successful authentication. This action generates a browser error page, which would normally seem harmless. However, embedded within the URL of this error page is the highly sensitive authorization code. The final piece of the attack relies on social engineering, where the attacker convinces the user—often under the guise of troubleshooting the “error”—to copy the entire contents of the address bar and share it, thereby delivering the session key directly into the attacker’s hands.
An Evolved and Insidious Threat
ConsentFix represents a dangerous evolution of a previously documented technique known as ClickFix. While both attacks manipulate OAuth flows, ConsentFix is more insidious because it entirely avoids suspicious consent screens that might alert a savvy user. Its success hinges on manipulating the legitimate authentication process itself, rather than exploiting a traditional software vulnerability. This makes it exceptionally difficult to patch in a conventional sense, as the components being abused are all functioning exactly as they were designed. The true danger of this method is its ability to remain invisible to many layers of a modern security stack. Since the initial login is performed legitimately by the victim from a trusted device and a known location, it satisfies robust security measures like Conditional Access policies and device compliance checks. Consequently, the first stage of the attack generates no alerts. The attacker’s subsequent use of the stolen code happens non-interactively, blending in with normal back-end system traffic and evading detection by tools that are not specifically configured to correlate these distinct events.
A Playbook for Unmasking the Attacker
Detecting this stealthy attack requires a specific and timely approach to log analysis. A successful ConsentFix intrusion leaves a distinct two-part signature in Microsoft Entra sign-in logs. The first event is a legitimate interactive sign-in, which shows the victim’s IP address, location, and device details, with all Conditional Access policies marked as successful. The second event, occurring within minutes, is a non-interactive sign-in that uses the stolen authorization code to redeem an access token. This second event will originate from the attacker’s infrastructure. The key to connecting these two seemingly unrelated activities is to correlate them using what can be termed a “correlation triad”: the SessionID, ApplicationID, and UserID. These three identifiers will be identical across both the victim’s interactive login and the attacker’s non-interactive token redemption. The definitive indicator of compromise is the discrepancy in the originating IP addresses and locations between these two correlated events. This race against time is critical, as defenders must correlate these logs and identify the anomaly within the authorization code’s ten-minute validity window to detect and respond to the attack in near real-time.
The emergence of the ConsentFix attack underscored a pivotal shift in the threat landscape, where the manipulation of trusted processes became as dangerous as the exploitation of software flaws. It served as a stark reminder that even the most secure authentication systems could be undermined by exploiting the weakest link: human trust. Security teams realized that defending against such threats required moving beyond perimeter controls and toward a more sophisticated model of behavioral analysis and rapid log correlation. This incident prompted a necessary evolution in defensive strategies, emphasizing that in the world of cloud security, visibility into the entire authentication lifecycle was no longer optional but essential for survival.