CVE-2024-7833: D-Link DI-8100 Firmware RCE Vulnerability

CVE-2024-7833 Overview

CVE-2024-7833 is a command injection vulnerability [CWE-77] affecting D-Link DI-8100 routers running firmware version 16.07. The flaw resides in the upgrade_filter_asp function within the upgrade_filter.asp file. Attackers can manipulate the path argument to inject arbitrary operating system commands. Exploitation occurs remotely over the network and requires low privileges. The exploit details have been publicly disclosed, increasing the likelihood of opportunistic attacks against exposed devices.

Critical Impact

Authenticated remote attackers can inject commands into the D-Link DI-8100 router, compromising router integrity, confidentiality, and availability.

Affected Products

• D-Link DI-8100 router (hardware)
• D-Link DI-8100 firmware version 16.07
• Deployments exposing the device web management interface to untrusted networks

Discovery Timeline

• 2024-08-15 - CVE-2024-7833 published to the National Vulnerability Database (NVD)
• 2024-08-19 - Last updated in the NVD database

Technical Details for CVE-2024-7833

Vulnerability Analysis

The vulnerability is a command injection weakness located in the firmware's web management interface. The upgrade_filter_asp function in upgrade_filter.asp processes a user-supplied path parameter without adequate sanitization. An attacker who can reach the management interface and authenticate with low privileges can append shell metacharacters to the parameter. The injected payload executes in the context of the underlying operating system process handling the request. Successful exploitation impacts confidentiality, integrity, and availability of the device, as reflected by the CVSS 4.0 vector's low impacts across all three properties. The EPSS score places this CVE in the top portion of vulnerabilities by predicted exploitation likelihood, signaling above-average attacker interest.

Root Cause

The root cause is improper neutralization of special elements used in an OS command [CWE-77]. The handler passes the attacker-controlled path argument into a shell or system call without escaping shell metacharacters such as ;, |, &, or backticks. This allows injected commands to be appended to the legitimate command string and executed by the firmware.

Attack Vector

The attack vector is network-based and targets the HTTP-based device management endpoint that serves upgrade_filter.asp. An attacker sends a crafted request containing shell metacharacters in the path parameter. No user interaction is required. The attack requires low privileges, consistent with an authenticated session on the router's administrative interface. Devices exposing management on WAN interfaces are at higher risk. See the GitHub PDF Resource and VulDB entry #274731 for additional technical details.

Detection Methods for CVE-2024-7833

Indicators of Compromise

• HTTP requests to upgrade_filter.asp containing shell metacharacters such as ;, |, &, $(), or backticks in the path parameter
• Unexpected outbound connections originating from the DI-8100 router shortly after requests to the management interface
• Modifications to router configuration, firmware, or DNS settings without authorized administrator activity

Detection Strategies

• Inspect web server and proxy logs in front of the router management interface for anomalous path parameter values targeting upgrade_filter.asp
• Deploy network IDS signatures that flag HTTP POST/GET traffic to upgrade_filter.asp containing command separators or shell syntax
• Monitor for repeated authentication attempts followed by access to administrative ASP endpoints, indicating credential abuse precursors

Monitoring Recommendations

• Forward router syslog and HTTP access logs to a centralized analytics platform for behavioral baselining
• Alert on configuration changes, firmware uploads, or new outbound flows from network infrastructure devices
• Track exposure of the DI-8100 management interface on WAN-facing IP addresses using attack surface monitoring

How to Mitigate CVE-2024-7833

Immediate Actions Required

• Restrict access to the DI-8100 web management interface to trusted internal management VLANs only
• Disable WAN-side administrative access and disable remote management features that are not required
• Rotate administrator credentials and enforce strong, unique passwords on all router accounts
• Audit recent administrative activity and HTTP requests against upgrade_filter.asp for signs of exploitation

Patch Information

No vendor advisory or patched firmware release is listed in the CVE data at the time of publication. Operators should monitor the D-Link security advisory portal for an official fix and apply firmware updates as soon as they become available. Until a patch is published, treat affected devices as high-risk and apply compensating controls.

Workarounds

• Place the DI-8100 behind a firewall that blocks inbound HTTP/HTTPS requests to the management interface from untrusted networks
• Apply ACLs that permit management interface access only from designated administrator IP addresses
• Consider replacing end-of-support or unpatched devices with current models that receive active security maintenance

# Example ACL restricting management access to a trusted subnet
# (adapt syntax to your edge firewall vendor)
deny  tcp any            host <DI-8100-IP> eq 80
deny  tcp any            host <DI-8100-IP> eq 443
permit tcp 10.10.10.0/24 host <DI-8100-IP> eq 80
permit tcp 10.10.10.0/24 host <DI-8100-IP> eq 443