Denial of Service in SyncBreeze Login via Oversized Password Parameter

Executive Summary

CVE-2023-53873 is a denial of service (DoS) vulnerability in SyncBreeze version 15.2.24. It occurs in the login authentication mechanism where an attacker can send an oversized password parameter containing repeated 'password=' values. This causes the login endpoint to become overwhelmed, leading to uncontrolled resource consumption that crashes the service and disrupts its availability. [2, 3]

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Impact Analysis

This vulnerability can impact you by causing a denial of service condition on the SyncBreeze service. An attacker can exploit it remotely without any privileges or user interaction by sending a specially crafted login request. This will crash or make the service unresponsive, disrupting availability and potentially halting file synchronization operations. [2, 3]

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Detection Guidance

This vulnerability can be detected by monitoring for unusual or malformed HTTP POST requests to the '/login' endpoint of the SyncBreeze web interface, specifically those containing an excessively long password parameter with repeated 'password=' values. A practical detection method is to capture and analyze network traffic for such patterns. For example, using a tool like tcpdump or Wireshark to filter HTTP POST requests to the login path and inspecting the payload for repeated 'password=' strings. Additionally, reviewing server logs for repeated login attempts with oversized password parameters can help identify exploitation attempts. A sample command to capture such traffic might be: tcpdump -A -s 0 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)' | grep 'POST /login' -A 10 | grep 'password=password=password=' [3]

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Mitigation Strategies

Immediate mitigation steps include restricting or blocking access to the SyncBreeze login endpoint from untrusted networks to prevent exploitation attempts. Applying input validation or rate limiting on the login endpoint to reject oversized or malformed password parameters can reduce risk. Upgrading SyncBreeze to a version later than 15.2.24, if available, is recommended to obtain official fixes. If an upgrade is not immediately possible, consider deploying network-level protections such as web application firewalls (WAFs) to detect and block malicious login requests containing repeated 'password=' parameters. Monitoring the service for crashes and restarting it promptly can also help maintain availability. [2, 3]

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Compliance Impact

The provided resources do not contain information regarding the impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

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