Attack Chain

1. Attacker identifies a vulnerable UTT HiPER 1250GW device running a susceptible firmware version (<= 3.2.7-210907-180535).
2. The attacker crafts a malicious HTTP POST request targeting the /goform/formNatStaticMap endpoint.
3. The POST request includes the NatBind argument with a value exceeding the buffer size allocated for it.
4. The vulnerable strcpy function within /goform/formNatStaticMap is called to copy the attacker-controlled NatBind argument into the undersized buffer.
5. The buffer overflow overwrites adjacent memory regions, potentially including function return addresses or other critical data.
6. The overwritten return address is replaced with an address pointing to attacker-controlled code.
7. When the vulnerable function returns, control is transferred to the attacker's code.
8. The attacker's code executes with the privileges of the web server process, potentially allowing for complete system compromise.

Impact

Successful exploitation of this vulnerability allows remote attackers to execute arbitrary code on affected UTT HiPER 1250GW devices. This can lead to complete device compromise, including unauthorized access to network resources, data theft, and denial-of-service conditions. Given the public availability of exploits, organizations using vulnerable devices are at high risk of being targeted.

Recommendation

• Apply available patches or firmware updates provided by UTT to address CVE-2026-5566.
• Monitor web server logs for suspicious POST requests to /goform/formNatStaticMap with unusually long NatBind arguments.
• Deploy the Sigma rule "Detect Suspicious NatBind Parameter Length" to identify potential exploitation attempts.
• Implement network segmentation to limit the impact of a compromised device.