CVE-2021-20049 in SMA100
Summary
by MITRE • 12/23/2021
A vulnerability in SonicWall SMA100 password change API allows a remote unauthenticated attacker to perform SMA100 username enumeration based on the server responses. This vulnerability impacts 10.2.1.2-24sv, 10.2.0.8-37sv and earlier 10.x versions.
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Analysis
by VulDB Data Team • 12/26/2021
This vulnerability resides within the SonicWall SMA100 secure access manager device family, specifically affecting firmware versions 10.2.1.2-24sv through 10.2.0.8-37sv and earlier 10.x releases. The issue manifests in the password change API endpoint which fails to properly validate authentication requests, creating a pathway for remote attackers to enumerate valid usernames through differential response analysis. The flaw represents a significant security weakness that directly violates the principle of least privilege and authentication security controls that should prevent unauthorized access to user account information.
The technical exploitation occurs through the password change API interface where the system responds differently to requests containing valid versus invalid usernames. When an attacker submits a username to the API endpoint, the server provides distinct error messages or response codes that indicate whether the target account exists within the system. This information disclosure vulnerability stems from inadequate input validation and response handling within the authentication framework, allowing attackers to systematically test usernames and determine which accounts are active on the system. The vulnerability aligns with CWE-200, which addresses information exposure through improper error handling, and specifically demonstrates weaknesses in authentication mechanisms that fail to provide consistent responses to malicious inputs.
The operational impact of this vulnerability extends beyond simple username enumeration, as it provides attackers with critical reconnaissance data that can facilitate subsequent attack phases. Once valid usernames are identified, attackers can proceed with password spraying, brute force attacks, or social engineering campaigns targeting specific accounts. This vulnerability particularly affects organizations relying on SonicWall SMA100 devices for remote access management, potentially compromising VPN access points and creating lateral movement opportunities within network perimeters. The attack surface is further expanded when considering that these devices often serve as primary gateways for remote workforce access, making them attractive targets for threat actors seeking persistent network presence.
Organizations should immediately implement mitigations including firmware updates to versions that address this vulnerability, network segmentation to isolate affected devices, and monitoring for anomalous API access patterns that might indicate enumeration attempts. The ATT&CK framework categorizes this vulnerability under T1078 Valid Accounts and T1566 Phishing, as it enables attackers to acquire legitimate credentials that can be used for privilege escalation and persistent access. Additional defensive measures should include implementing rate limiting on authentication endpoints, configuring intrusion detection systems to monitor for username enumeration patterns, and conducting regular security assessments of remote access infrastructure. The vulnerability demonstrates the critical importance of proper error handling and authentication response consistency in preventing information leakage that could compromise entire network security postures.