Attack Chain

1. An attacker identifies a vulnerable SAT CFDI 3.3 instance.
2. The attacker crafts a malicious POST request targeting the /signIn endpoint.
3. The attacker injects SQL code into the id parameter of the POST request. This is achieved by exploiting the lack of proper sanitization of the 'id' parameter.
4. The server executes the injected SQL code against the application's database. The attacker leverages boolean-based blind, stacked queries, or time-based blind SQL injection techniques to bypass security measures.
5. Through successful SQL injection, the attacker extracts sensitive data, such as user credentials, financial records, or other confidential information stored in the database.
6. Alternatively, the attacker may use SQL injection to modify data within the database, potentially leading to fraudulent transactions or data corruption.
7. The attacker could potentially leverage database access to gain shell access to the underlying server, leading to a complete system compromise.

Impact

Successful exploitation of this SQL injection vulnerability could result in the extraction of sensitive data, including financial records and user credentials. This can lead to financial loss, identity theft, and reputational damage. In more severe cases, attackers could gain control of the entire application and its underlying server. The number of potential victims is dependent on the number of organizations utilizing the vulnerable SAT CFDI 3.3 software.

Recommendation

• Apply any available patches or updates for SAT CFDI 3.3 to address CVE-2018-25202 immediately.
• Implement input validation and sanitization for all user-supplied data, especially within the signIn endpoint, to prevent SQL injection attacks.
• Deploy the Sigma rule "Detect Suspicious SAT CFDI SignIn SQL Injection Attempts" to your SIEM to monitor for exploitation attempts against the /signIn endpoint.
• Regularly review and update web application firewall (WAF) rules to block known SQL injection payloads and patterns.