CVE-2024-12084: Critical Heap-Based Buffer Overflow in rsync Daemon

 Critical Heap-Based Buffer Overflow in rsync Daemon

 CVE-2024-12084

CVE-2024-12084 is a critical vulnerability identified in the rsync daemon, classified with a CVSS v3.1 score of 9.8, indicating its severe impact on system security. This vulnerability is characterized as a heap-based buffer overflow, which arises from improper handling of attacker-controlled checksum lengths (specifically, the s2length variable) in the rsync codebase. (Jan 15, 2025)

Technical Details

The root cause of this vulnerability lies in the way the rsync daemon processes checksum lengths. When the maximum digest length ("MAX_DIGEST_LEN") exceeds a fixed value ("SUM_LENGTH", "which is 16 bytes"), it allows an attacker to write outside the bounds of the "sum2 buffer". This can lead to various malicious outcomes, including arbitrary code execution, data corruption, or denial of service.

Affected Versions

The vulnerability affects versions of rsync from 3.2.7 up to but not including 3.4.0. Users running these versions are at risk and should prioritize updating their software to mitigate potential exploitation.

Potential Impact

Exploitation Scenarios

1. Remote Code Execution: An attacker with anonymous read access to a vulnerable rsync server can exploit this flaw to execute arbitrary code on the server. For instance, if an organization uses rsync for public file distribution, an attacker could manipulate checksum lengths during file transfers to gain control over the server.
2. Data Corruption: By writing out of bounds in the sum2 buffer, an attacker could corrupt critical data structures within the rsync daemon, potentially leading to data loss or system instability.
3. Denial of Service: The exploitation of this vulnerability could also result in denial-of-service conditions, where legitimate users are unable to access rsync services due to crashes or unresponsive behavior caused by the attack.

Mitigation Strategies

Immediate Actions

• Update Software: The most effective way to mitigate this vulnerability is to update rsync to version 3.4.0 or later, where patches have been applied to address this issue.
• Disable Vulnerable Features: As a temporary workaround until updates can be applied, users can disable SHA* support by compiling with specific flags:

  bash
  CFLAGS=-DDISABLE_SHA512_DIGEST
  CFLAGS=-DDISABLE_SHA256_DIGEST
  

Long-Term Considerations

• Regular Audits: Organizations should conduct regular security audits of their systems and software dependencies to identify and remediate vulnerabilities proactively.
• Network Security Practices: Implementing strict access controls and monitoring network traffic can help detect and prevent unauthorized access attempts that may exploit vulnerabilities like CVE-2024-12084.

Conclusion

CVE-2024-12084 represents a significant security risk for systems utilizing the rsync daemon, particularly those exposed to public networks. Immediate action is required to update affected systems and mitigate potential exploits that could lead to severe consequences for data integrity and system availability. Organizations should prioritize regular updates and security best practices to safeguard their infrastructure against such vulnerabilities.