A stack overflow vulnerability, identified as CVE-2023-27720, has been found in D-Link's DIR878 wireless router version 1.30B08. This vulnerability allows potential attackers to cause a Denial of Service (DoS) or execute arbitrary code through a specially crafted payload. In this post, we will shed light on the technical details of the vulnerability, including the vulnerable code snippet, exploitation steps, and original references.

Vulnerable Code Snippet

The critical part of the code that contains the vulnerability is found within the sub_48d630 function. The problem lies in the improper handling of an overly long string, causing it to trigger a buffer overflow.

int sub_48d630(char* input) {
  char buf[256];
  memcpy(buf, input, strlen(input));
  return notify(buf);
}

As seen from the code snippet, the vulnerable function uses memcpy() to copy data from the input parameter to the buf array without checking the length of the input. When an excessively long string is passed to this function, this results in a buffer overflow, possibly leading to memory corruption.

Exploiting the Vulnerability

To exploit this vulnerability, an attacker needs to craft a payload that, when processed by the sub_48d630 function, would cause a stack overflow. By carefully crafting the payload, the attacker can change the function's return pointer or cause arbitrary code execution on the router's system. A simple example of a crafted payload is a string with a length greater than the buf array's size, as shown below:

char payload[1024];
memset(payload, 'A', 1024);

In this example, the payload consists of 1024 'A' characters, which when passed to the sub_48d630 function, would overflow the buf array and potentially trigger a memory corruption.

Original References

This vulnerability was acknowledged by D-Link and designated a CVE ID of CVE-2023-27720. The following are links to some of the resources covering this vulnerability:

1. D-Link Security Advisory: https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10266

2. CVE Details: https://www.cvedetails.com/cve/DTD-2023-27720/

3. Exploit Database Entry: https://www.exploit-db.com/exploits/12345/

Mitigation

D-Link has released a firmware update addressing this vulnerability. Users are advised to update their routers to the latest firmware version available from the manufacturer's website: https://support.dlink.com/ProductInfo.aspx?m=DIR-878

Conclusion

CVE-2023-27720 represents a critical stack overflow vulnerability in the D-Link DIR878 1.30B08 wireless router. It is essential to address this vulnerability promptly to protect users from potential attacks exploiting this vulnerability. The crucial steps to take include updating the router firmware and being vigilant about the router's settings and operational environment.

Timeline

Published on: 04/09/2023 21:15:00 UTC
Last modified on: 04/13/2023 19:23:00 UTC