CVE-2021-47848: Blitar Tourism 1.0 Auth Bypass Flaw

CVE-2021-47848 Overview

CVE-2021-47848 is a SQL Injection vulnerability affecting Blitar Tourism version 1.0, a tourism booking application. The vulnerability exists in the authentication mechanism and allows attackers to bypass login controls by injecting malicious SQL code through the username parameter. By crafting a specially designed username input, attackers can manipulate the underlying SQL query to gain unauthorized administrative access to the application without valid credentials.

Critical Impact

Attackers can completely bypass authentication controls, gaining full administrative access to the Blitar Tourism application, potentially exposing sensitive user data and allowing unauthorized manipulation of booking records and system configurations.

Affected Products

• Blitar Tourism version 1.0

Discovery Timeline

• 2026-01-21 - CVE CVE-2021-47848 published to NVD
• 2026-01-21 - Last updated in NVD database

Technical Details for CVE-2021-47848

Vulnerability Analysis

This vulnerability falls under CWE-89 (Improper Neutralization of Special Elements used in an SQL Command), commonly known as SQL Injection. The Blitar Tourism application fails to properly sanitize user-supplied input in the username field during the authentication process. When a user submits login credentials, the application directly incorporates the username value into an SQL query without adequate input validation or parameterized queries.

The authentication bypass is possible because the application constructs dynamic SQL statements that can be manipulated through carefully crafted input strings. An attacker can inject SQL syntax that alters the logic of the authentication query, effectively returning a true condition regardless of whether valid credentials are provided.

Root Cause

The root cause of this vulnerability is insufficient input validation and the use of string concatenation to build SQL queries in the login functionality. Instead of using prepared statements or parameterized queries that separate SQL code from user data, the application directly embeds user input into the query string. This allows malicious SQL fragments to be interpreted as part of the query structure rather than as data values.

Attack Vector

The attack vector is network-based, requiring no prior authentication or user interaction. An attacker can exploit this vulnerability remotely by sending a crafted HTTP request to the login endpoint. The malicious payload is delivered through the username parameter in the login form. By injecting SQL syntax such as ' OR '1'='1' -- or similar payloads, the attacker can manipulate the WHERE clause of the authentication query to always evaluate as true, thereby bypassing the credential check entirely.

The vulnerability is documented in publicly available resources including an entry on Exploit-DB #49759 and the VulnCheck Security Advisory. The source code is available on the GitHub Repository.

Detection Methods for CVE-2021-47848

Indicators of Compromise

• Unusual login patterns showing successful authentication with abnormally formatted usernames containing SQL syntax characters such as single quotes, double dashes, or OR statements
• Multiple failed login attempts followed by sudden successful authentication from the same source IP
• Web server logs containing SQL keywords (SELECT, OR, UNION, DROP) within username parameters
• Database audit logs showing unexpected query patterns during authentication events

Detection Strategies

• Deploy Web Application Firewall (WAF) rules to detect and block common SQL injection patterns in login form submissions
• Implement application-level logging that captures all authentication attempts with full parameter values for forensic analysis
• Configure intrusion detection systems (IDS) with signatures for SQL injection attack patterns targeting authentication endpoints
• Enable database query logging to identify anomalous or malformed queries executed during login operations

Monitoring Recommendations

• Monitor authentication logs for patterns consistent with SQL injection attempts, such as special characters in username fields
• Set up alerts for successful logins that occur without corresponding valid credential verification in application logs
• Conduct regular reviews of web server access logs focusing on POST requests to login endpoints with suspicious payloads
• Implement real-time monitoring for database error messages that may indicate SQL syntax errors from injection attempts

How to Mitigate CVE-2021-47848

Immediate Actions Required

• Remove or disable public access to the Blitar Tourism 1.0 application until remediation is complete
• Implement a Web Application Firewall (WAF) with SQL injection protection rules as a temporary defensive measure
• Review authentication logs for any signs of prior exploitation and compromised accounts
• Reset all administrative credentials and audit user accounts for unauthorized changes

Patch Information

No official vendor patch has been identified for this vulnerability. The application appears to be an open-source project hosted on GitHub. Organizations using this software should consider implementing their own fixes by modifying the authentication code to use parameterized queries or prepared statements. Alternative solutions include migrating to a more actively maintained tourism booking platform with proper security controls.

Workarounds

• Replace dynamic SQL query construction with parameterized queries or prepared statements in the login module
• Implement strict input validation on the username field, rejecting any input containing SQL special characters or keywords
• Deploy a reverse proxy or WAF configured to filter SQL injection patterns before requests reach the application
• Restrict network access to the application to trusted IP ranges only until a proper fix is implemented
• Consider using an authentication middleware or library that provides built-in protection against injection attacks

# Example WAF rule for ModSecurity to block SQL injection in login forms
SecRule ARGS:username "@detectSQLi" \
    "id:1001,\
    phase:2,\
    deny,\
    status:403,\
    log,\
    msg:'SQL Injection attempt detected in username parameter',\
    tag:'attack-sqli'"