A recent vulnerability has surfaced, affecting the firmware of a popular router brand, TP-LINK. Code CVE-2022-25060 identifies this vulnerability that impacts the specific router model TL-WR840N(ES)_V6.20_180709. The vulnerability stems from a command injection attack on the oal_startPing component. This post will delve into the details of the vulnerability, sample code snippets, and exploitation techniques. All original references, including the respective CVE links, are provided at the end of this post.

What is the oal_startPing Component?

The oal_startPing component is part of the firmware codebase of the TP-LINK TL-WR840N(ES)_V6.20_180709 router. This component is responsible for conducting network tests and sending diagnostic data signals across the network using ICMP echo requests.

Vulnerability Analysis

It was determined that the oal_startPing is susceptible to command injection attacks. A command injection attack allows an attacker to inject and execute arbitrary commands within the context of a vulnerable application. In this case, the attacker is able to execute arbitrary system commands with root-level access on the TP-LINK router, leading to complete control over the router's functionality and potentially, the connected devices.

The vulnerability is primarily due to insufficient input validation and sanitization in the oal_startPing component. Unsanitized user input can be embedded into a command that the router's firmware subsequently executes. This allows an attacker to insert arbitrary malicious commands into the input, resulting in unintended consequences.

The affected code snippet in the oal_startPing component can be found below

int oal_startPing (void) {
  char cmd[256];                                                      
  char buf [256];                                                  
  int r;                                                        

  parseConfigurationFile("dns_ping_target.conf", buf, 256);

  snprintf(cmd, sizeof(cmd), "ping -c %d -s %d -W %d %s", g_count, g_size, g_wtime, buf);

  r = system(cmd);
  return r;
}

As seen in the code snippet, the parseConfigurationFile function reads values from a configuration file dns_ping_target.conf. The contents of the configuration file are later passed to the snprintf function, allowing an attacker to manipulate the configuration file with malicious commands.

Exploit Steps

1. Assuming the attacker has access to the router's web interface, they can navigate to the Diagnostics page containing the oal_startPing component.

2. By manipulating the dns_ping_target.conf file with arbitrary commands, an attacker can inject malicious code to be executed by the router's system.

3. Once the attacker triggers the execution of oal_startPing, the router processes the malicious commands, providing the attacker root-level access and control.

Mitigation

At the time of writing, TP-LINK has not issued a patch to address the CVE-2022-25060 vulnerability. However, there are some steps users can take to protect themselves:

1. Limit access to the router's web interface, and ensure that only trusted users can manage the router's settings.

2. Regularly update the router's firmware to the latest version, as this may include patches for known vulnerabilities.

Original References

1. CVE-2022-25060 entry: [https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-25060]
2. National Vulnerability Database (NVD): [https://nvd.nist.gov/vuln/detail/CVE-2022-25060]

In conclusion, the command injection vulnerability CVE-2022-25060 poses a considerable risk to TP-LINK TL-WR840N(ES)_V6.20_180709 router users. Until TP-LINK addresses this issue with a firmware update, it is essential for users to take appropriate security measures, as discussed in the mitigation steps.

Timeline

Published on: 02/25/2022 20:15:00 UTC
Last modified on: 03/09/2022 14:38:00 UTC