CVE-2021-43099 : Exploit Details and Defense Strategies
Learn about the impact, technical details, and mitigation steps for CVE-2021-43099, an Archive Extraction vulnerability in bbs 5.3 that allows arbitrary code execution through directory traversal attacks.
An Archive Extraction (AKA "Zip Slip) vulnerability exists in bbs 5.3 in the UpgradeNow function in UpgradeManageAction.java, which unzips the arbitrary uploaded zip file without checking filenames. Exploitation involves specially crafted archives with directory traversal filenames like ../../evil.exe.
Understanding CVE-2021-43099
This CVE-2021-43099 involves a Zip Slip vulnerability in bbs 5.3, potentially enabling malicious actors to execute arbitrary code.
What is CVE-2021-43099?
CVE-2021-43099 is an Archive Extraction vulnerability in bbs 5.3 that allows unverified unzipping of uploaded files, paving the way for directory traversal attacks.
The Impact of CVE-2021-43099
- Malicious actors can exploit the vulnerability by uploading specially crafted archives with directory traversal filenames, leading to arbitrary code execution on the system.
Technical Details of CVE-2021-43099
This section delves into the specifics of the vulnerability.
Vulnerability Description
The vulnerability lies in the UpgradeNow function in UpgradeManageAction.java within bbs 5.3, which fails to validate filenames during the unzipping process, allowing for directory traversal attacks.
Affected Systems and Versions
- Affected: bbs 5.3
- Unaffected: Not specified
Exploitation Mechanism
- Attackers can exploit the vulnerability by uploading archives containing directory traversal filenames such as ../../evil.exe.
Mitigation and Prevention
Protecting systems from CVE-2021-43099 is crucial for security.
Immediate Steps to Take
- Apply security patches provided by the vendor to mitigate the vulnerability.
- Implement file upload validations to prevent directory traversal exploits.
Long-Term Security Practices
- Regularly update and patch software to address known vulnerabilities.
- Train developers and IT staff on secure coding practices to prevent similar issues.
Patching and Updates
- Stay informed about security advisories and updates from the software vendor to apply patches promptly.