Authenticated code execution via oversized FTP directory command
Published Nov 9, 2021 · Updated Aug 3, 2024
Stack-based buffer overflow in Siemens Nucleus FTP server allows remote authenticated users to execute code or crash devices. The MKD/XMKD handler fails to validate command length before processing attacker-controlled directory names, allowing oversized input to overwrite stack memory. FTP access and valid credentials are required; the service is disabled by default on Desigo products, and exploitation can interrupt control functions or run code in the device context.
Summary
What happened
Stack-based buffer overflow in Siemens Nucleus FTP server allows remote authenticated users to execute code or crash devices. The MKD/XMKD handler fails to validate command length before processing attacker-controlled directory names, allowing oversized input to overwrite stack memory. FTP access and valid credentials are required; the service is disabled by default on Desigo products, and exploitation can interrupt control functions or run code in the device context.
The record
- CVE
- CVE-2021-31888
- Published
- Nov 9, 2021
- Updated
- Aug 3, 2024
- Vendor
- Siemens
- Product
- TALON TC Compact (BACnet)
- Classifications
- CWE-787, CWE-170, T1190
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Nov 9, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=All versions < V3.5.4
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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