CVE-2021-35247 is a medium-severity vulnerability affecting SolarWinds Serv-U. This vulnerability allows improper input validation for the LDAP authentication web login screen, potentially allowing attackers to manipulate input in a way that is not properly sanitized. The issue arises from the web login screen's failure to validate and sanitize input adequately. Although SolarWinds has updated the input mechanism to enhance validation and sanitization, organizations must be aware that improper characters were previously permitted.
Published on January 10, 2022, this vulnerability has a CVSS score of 4.3, indicating a medium severity level. The attack vector is network-based, with low attack complexity and no required privileges for exploitation. User interaction is necessary for successful exploitation, making it critical for organizations to address this vulnerability in a timely manner.
Risk to organizations includes potential unauthorized access and data integrity issues due to inadequate input validation. Attackers may leverage this vulnerability to manipulate LDAP queries, resulting in unintended behavior. Organizations should prioritize patching immediately to mitigate the risk associated with this vulnerability.
As of now, there is no known public exploit available, and the vulnerability is included in the Known Exploited Vulnerabilities catalog, which indicates that it is actively tracked for potential exploitation. Organizations are urged to follow the vendor's guidance to ensure full remediation and protect their systems.
Vulnerability Details
The official description of CVE-2021-35247 states: "Serv-U web login screen to LDAP authentication was allowing characters that were not sufficiently sanitized. SolarWinds has updated the input mechanism to perform additional validation and sanitization. Please Note: No downstream affect has been detected as the LDAP servers ignored improper characters. To ensure proper input validation is completed in all environments, SolarWinds recommends scheduling an update to the latest version of Serv-U."
This vulnerability is classified under CWE-20, which refers to improper input validation. The CVSS score of 4.3 reflects its medium severity, indicating that while it is not critical, it still poses a significant risk. The affected product is SolarWinds Serv-U, specifically versions prior to 15.3.
Technical Analysis
The root cause of this vulnerability lies in the inadequate sanitization of characters in the LDAP authentication input. This allows an attacker to craft requests that bypass normal validation checks. The attack vector is network-based, meaning an attacker can exploit this vulnerability remotely without physical access to the targeted system.
The attack complexity is low, requiring no special conditions for exploitation, although user interaction is necessary for an attacker to successfully execute the attack. The potential impacts include a low level of integrity impact, as erroneous input may lead to unexpected behavior in the application.
Risk & Impact Analysis
Real-world deployment of this vulnerability may expose organizations to significant risks, including unauthorized access to sensitive systems and potential data manipulation. The blast radius is particularly concerning for organizations relying on SolarWinds Serv-U for critical operations, as an attacker could exploit this vulnerability to gain control over sensitive user data or system configurations.
Given the CVSS score of 4.3, organizations should address this vulnerability in their priority patch cycle. The urgency is heightened by its inclusion in the KEV catalog, indicating that it is actively monitored for exploitation attempts. Organizations that fail to patch may find themselves at risk of exploitation.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | Yes |
Ransomware Use | No |
Affected Versions
The affected versions of SolarWinds Serv-U are all versions prior to 15.3. Organizations currently using these versions should prioritize upgrading to the latest version to mitigate the vulnerability.
Mitigation & Remediation
Organizations should apply the latest updates as recommended by SolarWinds to address this vulnerability. For those unable to immediately upgrade, implementing additional input validation and sanitization measures in their applications can help mitigate potential exploitation. It is also advisable to review and harden network configurations to limit exposure of the Serv-U application.
For further guidance, organizations may consider performing a comprehensive security assessment to identify and address similar vulnerabilities across their systems. Continuous penetration testing can also be beneficial in identifying weaknesses before they can be exploited.
Learn more about conducting effective penetration testing through penetration testing services.
Detection Guidance
Organizations should monitor logs for indicators of unauthorized access attempts and any unusual behavior associated with the Serv-U application. Behavioral anomalies, such as unexpected input patterns or system responses, may also indicate attempts to exploit this vulnerability.
Network signatures that identify unusual requests to the LDAP authentication endpoint can assist in early detection of potential exploitation attempts.
AppSecure Threat Intelligence Insight
CVE-2021-35247 highlights the importance of robust input validation across applications, especially those handling sensitive authentication processes. Organizations should leverage this vulnerability as a learning opportunity to strengthen their security posture and improve input validation practices.
Monitoring trends in vulnerabilities like CVE-2021-35247 can inform better security practices. Organizations should consider adopting a proactive security strategy that includes regular assessments and updates to their security protocols.
For a comprehensive understanding of vulnerability management, organizations may refer to the vulnerability management program design.
Additionally, the importance of conducting regular penetration testing cannot be overstated to ensure that security mechanisms are effective.
Finally, organizations can benefit from understanding the latest trends in vulnerability exposure and mitigation strategies by reviewing resources on vulnerability exposure and how to address them.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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