CVE-2015-0857 – CVE-2015-0857 is a command injection vulnerabil... (How to Fix)

Q: What is the severity of CVE-2015-0857?

CVE-2015-0857 has a CVSS score of 9.8 (CRITICAL). CVE-2015-0857 is a command injection vulnerability in Cool Projects TarDiff that allows remote attackers to execute arbitrary commands via shell metacharacters in tar file names or file names within tar archives. This affects systems using vulnerable versions of TarDiff to process untrusted tar files. Attackers can achieve remote code execution with the privileges of the TarDiff process.

📋 TL;DR

CVE-2015-0857 is a command injection vulnerability in Cool Projects TarDiff that allows remote attackers to execute arbitrary commands via shell metacharacters in tar file names or file names within tar archives. This affects systems using vulnerable versions of TarDiff to process untrusted tar files. Attackers can achieve remote code execution with the privileges of the TarDiff process.

💻 Affected Systems

Products:

Cool Projects TarDiff

Versions: All versions before the fix commits in 2016

Operating Systems: Linux, Unix-like systems

Default Config Vulnerable: ⚠️ Yes

Notes: Vulnerable when processing tar files with shell metacharacters in file names. The vulnerability is in how TarDiff passes file names to shell commands.

📦 What is this software?

Debian Linux by Debian

View all CVEs affecting Debian Linux →

Tardiff by Tardiff Project

View all CVEs affecting Tardiff →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Full system compromise with root privileges if TarDiff runs as root, allowing attackers to install backdoors, exfiltrate data, or pivot to other systems.

🟠

Likely Case

Remote code execution with the privileges of the user running TarDiff, enabling data theft, lateral movement, or denial of service.

🟢

If Mitigated

Limited impact if TarDiff runs in a sandboxed environment with minimal privileges and processes only trusted tar files.

🌐 Internet-Facing: HIGH if TarDiff processes user-uploaded tar files from the internet, as exploitation requires no authentication.

🏢 Internal Only: MEDIUM if TarDiff processes tar files from internal sources only, but still poses risk from insider threats or compromised internal systems.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Exploitation is straightforward by crafting tar files with malicious file names containing shell metacharacters like semicolons, backticks, or command substitutions.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Versions including commits 9bd6a07bc204472ac27242cea16f89943b43003a and a18e8df51511df276e61dbccdbe1714fc53af965

Vendor Advisory: http://www.debian.org/security/2016/dsa-3562

Restart Required: No

Instructions:

1. Update TarDiff to a patched version from the official repository. 2. For Debian systems, apply security update via 'apt-get update && apt-get upgrade tardiff'. 3. Verify the fix by checking the commit hash includes the security patches.

🔧 Temporary Workarounds

Input validation and sanitization

linux

Implement custom validation to reject tar files with shell metacharacters in file names before processing with TarDiff.

#!/bin/bash
# Example script to check tar file names
if tar -tf "$1" | grep -q "[;&|`$()]" ; then
    echo "Rejecting tar file with suspicious characters"
    exit 1
fi

Run TarDiff with restricted privileges

linux

Execute TarDiff as a low-privilege user in a chroot or container to limit damage if exploited.

sudo -u nobody tardiff [options]

🧯 If You Can't Patch

Disable TarDiff usage for processing untrusted tar files entirely.
Implement network segmentation to isolate systems running vulnerable TarDiff versions.

🔍 How to Verify

Check if Vulnerable:

Check TarDiff version and commit history. If using Git, verify if security commits are present: 'git log --oneline | grep -E "9bd6a07|a18e8df"'.

Check Version:

tardiff --version 2>/dev/null || dpkg -l tardiff 2>/dev/null || rpm -q tardiff 2>/dev/null

Verify Fix Applied:

Test with a tar file containing shell metacharacters in file names. If TarDiff rejects it or processes it safely without command execution, the fix is likely applied.

📡 Detection & Monitoring

Log Indicators:

Unusual shell commands executed by the TarDiff process
Error messages related to tar file processing failures
Unexpected process spawns from TarDiff

Network Indicators:

Outbound connections from systems running TarDiff to unexpected destinations
Unusual data exfiltration patterns

SIEM Query:

process.name:"tardiff" AND (process.cmdline:*[;&|`$()]* OR process.parent.name:"tardiff")

📊 Metadata

CVE ID: CVE-2015-0857

CVSS v3 Score: 9.8 (CRITICAL)

CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-77

Published: May 6, 2016

Last Updated: April 12, 2025

🔗 References

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🔗 Related Vulnerabilities

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