CVE-2017-9982 in TeamSpeak
Summary
by MITRE
TeamSpeak Client 3.0.19 allows remote attackers to cause a denial of service (application crash) via the ᗪ Unicode character followed by the ༿ Unicode character.
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Analysis
by VulDB Data Team • 12/29/2019
The vulnerability identified as CVE-2017-9982 represents a denial of service flaw within the TeamSpeak Client software version 3.0.19. This issue arises from the client's inadequate handling of specific Unicode character sequences during message processing and display operations. The affected system demonstrates a critical weakness in input validation and string parsing mechanisms that fails to properly sanitize Unicode data before rendering it within the application interface.
The technical exploitation of this vulnerability occurs through a carefully crafted sequence involving the Unicode character represented as 5610 followed by the Unicode character 3903. When these specific characters are processed by the TeamSpeak client, the application's internal parsing logic encounters unexpected behavior that leads to memory corruption or stack overflow conditions. This particular character combination triggers a flaw in the client's text rendering engine where the Unicode handling routines fail to properly account for the interaction between these specific code points, resulting in an application crash that terminates the client process.
From an operational perspective, this vulnerability presents a significant risk to users who may inadvertently encounter maliciously crafted messages containing the vulnerable character sequence. The denial of service impact extends beyond simple client disruption as it can potentially be leveraged in broader attack scenarios where attackers might use this vulnerability to repeatedly crash client applications, effectively preventing legitimate users from communicating within TeamSpeak channels. The vulnerability affects the availability of the service and can be exploited by remote attackers without requiring authentication or privileged access to the system.
The underlying flaw aligns with CWE-129, which addresses improper validation of input boundaries, and CWE-170, which covers issues with improper handling of Unicode characters in software applications. The vulnerability also maps to ATT&CK technique T1499.004 which covers network denial of service attacks through the exploitation of application vulnerabilities. The root cause stems from insufficient input sanitization and the absence of proper Unicode normalization routines within the client's message processing pipeline, leaving the application susceptible to malformed character sequences that can trigger unexpected program behavior.
Mitigation strategies for this vulnerability include immediate deployment of the vendor-provided security patch that addresses the Unicode parsing issue within the TeamSpeak client. Organizations should implement network monitoring to detect and block malicious messages containing the specific vulnerable character sequences. Additionally, users should be educated about the risks of accepting messages from untrusted sources and the importance of keeping client software updated. The recommended approach involves comprehensive input validation that includes Unicode character range checking and proper error handling for malformed sequences, ensuring that the application gracefully handles unexpected input rather than crashing. System administrators should also consider implementing message filtering mechanisms at network boundaries to prevent the propagation of potentially malicious Unicode sequences through the TeamSpeak infrastructure.