CVE-2018-25339: Zechat 1.5 SQL Injection Vulnerability

CVE-2018-25339 Overview

CVE-2018-25339 is a SQL injection vulnerability in Zechat 1.5, a web-based chat application from Bylancer. The flaw resides in the v parameter, which fails to sanitize user-supplied input before passing it into a backend SQL query. Unauthenticated attackers can deliver time-based blind SQL injection payloads to confirm the vulnerability and extract data from the underlying database. The issue is classified under CWE-89 (Improper Neutralization of Special Elements used in an SQL Command). A public exploit is documented in Exploit-DB #44685.

Critical Impact

Unauthenticated remote attackers can extract sensitive database contents from Zechat 1.5 over the network using time-based blind SQL injection against the v parameter.

Affected Products

• Zechat 1.5 (Bylancer)
• Deployments exposing the vulnerable v parameter endpoint
• Installations without input sanitization patches applied

Discovery Timeline

• 2026-05-17 - CVE-2018-25339 published to the National Vulnerability Database (NVD)
• 2026-05-18 - Last updated in NVD database

Technical Details for CVE-2018-25339

Vulnerability Analysis

The vulnerability stems from improper neutralization of user input passed to the v query parameter in Zechat 1.5. The application concatenates the parameter value directly into a SQL statement without parameterized queries or input validation. Attackers exploit this by submitting crafted payloads that alter the query's logic. Because no error output is required, attackers use time-based blind techniques relying on database SLEEP() functions to infer responses based on response latency.

Root Cause

The root cause is a failure to apply prepared statements or input sanitization on the v parameter before query execution. The application trusts attacker-controlled HTTP input as part of a SQL command, satisfying the conditions for [CWE-89]. Authentication is not enforced before the vulnerable code path executes, broadening the attack surface to any network-reachable client.

Attack Vector

An unauthenticated attacker sends HTTP requests to the vulnerable Zechat endpoint with malicious payloads in the v parameter. Using time-based blind injection, the attacker conditionally triggers SLEEP() calls to extract data one bit at a time. Response delays confirm whether a Boolean inference is true or false. Over many requests, attackers reconstruct database schemas, user credentials, and message content. The vulnerability is reachable over the network with low attack complexity and requires no user interaction. Technical details and a working proof of concept are published at Exploit-DB #44685 and the VulnCheck Advisory.

Detection Methods for CVE-2018-25339

Indicators of Compromise

• HTTP requests to Zechat endpoints containing the v parameter with SQL keywords such as SLEEP, BENCHMARK, UNION, SELECT, or encoded variants
• Unusually long response times from the Zechat application correlated with single-client request bursts
• Repeated requests from the same source iterating numeric or character ranges within the v parameter
• Database logs showing slow queries or unexpected SLEEP() invocations originating from the web application user

Detection Strategies

• Deploy web application firewall (WAF) rules that flag SQL injection signatures targeting the v query parameter
• Correlate web server access logs with database slow-query logs to identify time-based injection patterns
• Inspect outbound traffic from the Zechat host for data exfiltration attempts following injection activity

Monitoring Recommendations

• Alert on HTTP requests where the v parameter contains SQL meta-characters or function names
• Monitor application response time distributions for statistical anomalies tied to specific source IPs
• Forward web and database logs to a centralized analytics platform for retroactive hunting against published payload signatures

How to Mitigate CVE-2018-25339

Immediate Actions Required

• Restrict network access to Zechat 1.5 deployments using firewall rules or reverse proxy allowlists
• Deploy WAF signatures that block SQL injection payloads targeting the v parameter
• Audit database accounts used by Zechat and revoke any privileges beyond what the application strictly requires
• Review web and database logs for prior exploitation attempts referencing the Exploit-DB #44685 payload

Patch Information

No vendor patch is referenced in the available CVE data. Operators should consult the Bylancer Homepage for current product status and upgrade guidance. The VulnCheck Advisory provides additional remediation context.

Workarounds

• Place Zechat behind a WAF configured to block SQL injection payloads and time-based blind injection patterns
• Refactor or wrap the vulnerable endpoint to enforce strict input validation on the v parameter, rejecting non-expected character sets
• Run the Zechat database user under least privilege, removing access to administrative functions and non-essential schemas
• Consider migrating to a maintained chat platform if no vendor fix is forthcoming

# Example ModSecurity rule to block SQL keywords in the v parameter
SecRule ARGS:v "@rx (?i)(sleep|benchmark|union\s+select|--|/\*)" \
    "id:1002518,phase:2,deny,status:403,msg:'CVE-2018-25339 Zechat v parameter SQLi attempt'"