Executive Summary

This vulnerability exists in the TP-Link Archer C7 v5 and v5.8 models, specifically in the uhttpd modules of their web interface. The admin password is encrypted client-side using RSA-1024 before being sent to the router during login.

Because the RSA key length is only 1024 bits, an adjacent attacker who can intercept network traffic could potentially perform a brute-force or factorization attack to break the encryption and recover the plaintext administrator password.

This would allow unauthorized access to the device and compromise its configuration.

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Impact Analysis

If exploited, this vulnerability can lead to unauthorized access to your TP-Link Archer C7 router's administrative interface.

An attacker could intercept your network traffic, break the weak RSA-1024 encryption protecting the admin password, and recover the password in plaintext.

This unauthorized access could allow the attacker to change your router's configuration, potentially disrupting your network, intercepting or redirecting your internet traffic, or compromising connected devices.

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Compliance Impact

The vulnerability allows an adjacent attacker to recover the plaintext administrator password by exploiting inadequate encryption strength (RSA-1024) used in the TP-Link Archer C7 web interface. This unauthorized access could lead to compromise of device configuration and potentially sensitive data.

Such unauthorized access and potential data compromise could negatively impact compliance with common standards and regulations like GDPR and HIPAA, which require strong protection of administrative credentials and sensitive data to prevent unauthorized access.

However, the provided information does not explicitly state the direct impact on compliance with these standards.

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Detection Guidance

This vulnerability involves the interception of network traffic where the admin password is encrypted client-side using RSA-1024 before being sent to the router. Detection would involve monitoring network traffic for such encrypted login attempts to the TP-Link Archer C7 web interface.

Specifically, you can use network traffic capture tools like Wireshark or tcpdump to capture packets between clients and the router's web interface. Look for RSA-encrypted login data being transmitted.

• Use tcpdump to capture traffic on the router's IP and port 80 or 443 (depending on the web interface): tcpdump -i <interface> host <router_ip> and port 80
• Use Wireshark to analyze captured packets for RSA-encrypted login attempts.

Since the vulnerability is related to the RSA-1024 encryption strength, detecting attempts to brute-force or factorize the RSA key would require advanced cryptanalysis tools and is generally not feasible with simple commands.

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Mitigation Strategies

Immediate mitigation steps include restricting network access to the router's web interface to trusted devices only, especially preventing adjacent attackers from intercepting traffic.

Use a secure management network or VPN to access the router's interface to avoid exposure to adjacent attackers.

Since the vulnerability affects specific builds of the TP-Link Archer C7 (through Build 20220715), check for firmware updates or patches from TP-Link and apply them if available.

If no patch is available, consider replacing the device with a model that does not have this vulnerability or disabling remote management features.

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