CVE-2021-35005 in TeamViewer
Summary
by MITRE • 01/24/2022
This vulnerability allows local attackers to disclose sensitive information on affected installations of TeamViewer. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The specific flaw exists within the TeamViewer service. The issue results from the lack of proper validation of user-supplied data, which can result in a read past the end of an allocated array. An attacker can leverage this in conjunction with other vulnerabilities to execute arbitrary code in the context of SYSTEM. Was ZDI-CAN-13818.
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Analysis
by VulDB Data Team • 01/28/2022
The vulnerability identified as CVE-2021-35005 represents a critical information disclosure flaw within TeamViewer's service implementation that fundamentally compromises system security through improper input validation mechanisms. This vulnerability resides in the core service component of TeamViewer software, making it particularly dangerous as it affects the foundational security controls that protect remote access sessions. The flaw manifests when the system fails to properly validate user-supplied data during processing operations, creating a condition where memory access violations can occur. The specific technical manifestation involves a read past the end of an allocated array, which is a classic symptom of buffer over-read vulnerabilities that can expose sensitive memory contents to unauthorized access.
The exploitation chain for this vulnerability requires an initial foothold through low-privileged code execution, which aligns with common attack methodologies where adversaries first gain minimal system access before escalating privileges. This prerequisite makes the vulnerability particularly concerning in environments where privilege separation is not properly enforced or where users may be susceptible to social engineering attacks. The vulnerability's classification under CWE-125 indicates it falls within the category of out-of-bounds read conditions, which are frequently exploited in modern attack scenarios due to their ability to reveal sensitive information that can be leveraged for further exploitation. When combined with other vulnerabilities present in the system, this flaw can provide attackers with the necessary conditions to achieve SYSTEM-level privileges, representing a significant escalation in attack capabilities.
The operational impact of CVE-2021-35005 extends beyond simple information disclosure, as it creates a pathway for complete system compromise when exploited in conjunction with additional vulnerabilities. Attackers can potentially extract sensitive data from memory regions that contain credentials, session tokens, or other confidential information that could be used for lateral movement within networks. The vulnerability's nature as a local information disclosure means that it affects systems where TeamViewer is installed and running, making it particularly dangerous in enterprise environments where remote access solutions are widely deployed. The ZDI-CAN-13818 reference indicates this vulnerability was recognized by the Zero Day Initiative and underwent proper vulnerability coordination processes, highlighting its significance within the security community and the potential for widespread exploitation across various organizational targets.
Organizations should implement immediate mitigation strategies including patching the affected TeamViewer installations to address the root cause of the buffer over-read condition. System administrators should also consider implementing network segmentation and monitoring to detect anomalous behavior that might indicate exploitation attempts. The vulnerability's characteristics align with tactics described in the ATT&CK framework under privilege escalation and credential access domains, making defensive measures particularly important for organizations that rely heavily on remote access solutions. Regular security assessments and vulnerability scanning should be conducted to identify similar flaws in other remote access tools and services that may present comparable risks. Additionally, implementing proper input validation and memory safety controls in software development practices can help prevent similar vulnerabilities from being introduced in future versions of TeamViewer and other similar applications.