Executive Summary

CVE-2019-25611 is a buffer overflow vulnerability in the MiniFtp software, specifically in the parseconf_load_setting function. This function processes configuration settings by splitting an input string into two fixed-size buffers of 128 bytes each without proper bounds checking. If an attacker supplies configuration values exceeding 128 bytes, it causes a stack buffer overflow.

This overflow allows local attackers to overwrite the return address on the stack, enabling them to execute arbitrary code with root privileges by crafting a malicious miniftpd.conf file containing an overly long configuration line.

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Impact Analysis

This vulnerability allows a local attacker to escalate privileges by executing arbitrary code with root privileges on the affected system. By exploiting the buffer overflow in the configuration parser, an attacker can gain full control over the system running MiniFtp.

• Local privilege escalation
• Execution of arbitrary code with root privileges
• Potential full system compromise

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by checking the contents of the miniftpd.conf configuration file for any oversized configuration values, specifically lines where the value part exceeds 128 bytes.'}, {'type': 'paragraph', 'content': 'A practical detection method is to search for configuration lines with values longer than 128 characters, which could indicate an attempt to exploit the buffer overflow.'}, {'type': 'list_item', 'content': 'Use commands like `grep` and `awk` to find suspiciously long configuration values in miniftpd.conf, for example:'}, {'type': 'list_item', 'content': "`awk -F '=' '{ if(length($2) > 128) print $0 }' /path/to/miniftpd.conf`"}, {'type': 'list_item', 'content': 'Or use `grep` with a regex to find lines with long values:'}, {'type': 'list_item', 'content': "`grep -E '.{129,}' /path/to/miniftpd.conf`"}, {'type': 'paragraph', 'content': 'Additionally, monitoring for unexpected root shell executions or unusual process behavior related to MiniFtp could help detect exploitation attempts.'}] [1]

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Mitigation Strategies

Immediate mitigation steps include:

• Review and sanitize the miniftpd.conf configuration file to ensure no configuration values exceed 128 bytes.
• Restrict local access to the MiniFtp service to trusted users only, as the vulnerability requires local attacker access.
• If possible, apply patches or updates from the MiniFtp project that address this buffer overflow vulnerability.
• Monitor system logs and MiniFtp activity for signs of exploitation attempts.

As a longer-term solution, consider replacing MiniFtp with a more secure FTP server that does not have this vulnerability.

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