CVE-2018-7304 in Tiki
Summary
by MITRE
Tiki 17.1 does not validate user input for special characters; consequently, a CSV Injection attack can open a CMD.EXE or Calculator window on the victim machine to perform malicious activity, as demonstrated by an "=cmd|' /C calc'!A0" payload during User Creation.
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Analysis
by VulDB Data Team • 01/07/2020
The vulnerability identified as CVE-2018-7304 affects Tiki 17.1, a popular open-source content management system and wiki platform. This security flaw represents a critical input validation weakness that allows attackers to execute malicious commands through CSV injection techniques. The vulnerability specifically manifests during user creation processes where the application fails to properly sanitize user input containing special characters. The absence of proper input validation creates an exploitable vector that can be leveraged by malicious actors to compromise system integrity and execute unauthorized operations on victim machines.
The technical implementation of this vulnerability stems from inadequate sanitization of user-supplied data within the Tiki platform's user creation module. When users submit data containing special characters such as the equals sign, pipe symbol, and command execution indicators, the system processes these inputs without proper validation or encoding. The payload structure "=cmd|' /C calc'!A0" demonstrates how attackers can craft malicious input that when processed by the application, gets interpreted as a command to execute cmd.exe with the calc command. This particular payload exploits the way spreadsheet applications interpret formulas and data, where the equals sign at the beginning of a cell value triggers formula execution, while the pipe symbol and command structure enable system command invocation. This vulnerability operates at the intersection of web application security and spreadsheet security, creating a unique attack surface where web applications can inadvertently execute operating system commands through CSV data processing.
The operational impact of this vulnerability extends beyond simple command execution to encompass broader system compromise capabilities. When an attacker successfully exploits this vulnerability, they can potentially gain unauthorized access to system resources, escalate privileges, and execute arbitrary code on the victim machine. The demonstration of opening a calculator window represents a basic proof-of-concept that could easily be expanded to execute more dangerous payloads such as downloading malware, establishing reverse shells, or performing data exfiltration. The vulnerability affects the core user management functionality of Tiki, making it particularly dangerous as it can be exploited by both authenticated and unauthenticated attackers depending on the specific implementation. This weakness directly violates security principles outlined in the OWASP Top Ten, specifically addressing injection flaws and inadequate input validation. The vulnerability also aligns with ATT&CK technique T1059.003 for command and scripting interpreter, where adversaries leverage system command execution capabilities to achieve their objectives.
Mitigation strategies for CVE-2018-7304 require immediate implementation of proper input sanitization and validation mechanisms within the Tiki application. Organizations should implement comprehensive data validation that filters or escapes special characters before processing user input, particularly during user creation and data import operations. The solution must include proper encoding of potentially malicious characters such as equals signs, pipe symbols, and other command indicators that could trigger unintended system behavior. Security patches should be applied immediately to upgrade to versions of Tiki that address this vulnerability, as the fix typically involves implementing robust input validation routines that prevent the injection of dangerous payloads. Additionally, network segmentation and monitoring should be enhanced to detect unusual command execution patterns that might indicate exploitation attempts. The implementation of web application firewalls and input validation layers can provide additional protection against similar vulnerabilities. Organizations should also conduct thorough security testing including penetration testing and vulnerability scanning to identify other potential injection points within their Tiki installations and ensure that similar weaknesses have been addressed throughout the application codebase.