CVE-2024-33899: Rarlab WinRAR DOS Vulnerability

CVE-2024-33899 Overview

CVE-2024-33899 is an input validation vulnerability in RARLAB WinRAR versions prior to 7.00 that affects Linux and UNIX platforms. The vulnerability allows attackers to inject ANSI escape sequences, which can be used to spoof terminal screen output or cause a denial of service. This type of attack exploits the way terminal emulators interpret control characters embedded in filenames or archive metadata.

Critical Impact

Attackers can manipulate terminal output to deceive users or disrupt operations on Linux/UNIX systems running vulnerable WinRAR versions.

Affected Products

• RARLAB WinRAR versions before 7.00
• Linux Kernel (as the underlying operating system platform)
• OpenGroup UNIX systems (as affected platform)

Discovery Timeline

• 2024-04-29 - CVE-2024-33899 published to NVD
• 2025-06-20 - Last updated in NVD database

Technical Details for CVE-2024-33899

Vulnerability Analysis

This vulnerability stems from improper handling of ANSI escape sequences within WinRAR on Linux and UNIX platforms. When WinRAR processes archive contents containing specially crafted filenames or metadata with embedded ANSI escape codes, these sequences are passed directly to the terminal without sanitization. Terminal emulators interpret these escape sequences as control commands, allowing attackers to manipulate what users see on screen or potentially crash the terminal session.

The attack requires some level of user interaction as the victim must extract or list the contents of a malicious archive using WinRAR in a terminal environment. The vulnerability can lead to high confidentiality, integrity, and availability impacts when successfully exploited.

Root Cause

The root cause is classified as CWE-150: Improper Neutralization of Escape, Meta, or Control Sequences. WinRAR failed to properly sanitize or escape ANSI control sequences when displaying archive contents or processing filenames in terminal output on Linux and UNIX systems. This oversight allows arbitrary terminal control characters to be interpreted by the user's terminal emulator rather than being displayed as literal text.

Attack Vector

The attack is network-based, typically delivered through a malicious archive file containing crafted filenames with embedded ANSI escape sequences. An attacker could distribute such archives via email, file sharing platforms, or compromised websites. When a user extracts or views the archive contents using WinRAR in a terminal session, the embedded escape sequences execute in the context of the terminal, potentially:

• Overwriting displayed text to hide malicious filenames or actions
• Creating fake prompts to capture credentials
• Clearing terminal history or output
• Causing terminal crashes leading to denial of service

The vulnerability mechanism involves embedding ANSI escape codes within archive filenames. When WinRAR outputs these names to the terminal, the terminal interprets the escape sequences as commands rather than literal characters. For example, escape sequences could be used to move the cursor position, change colors, clear screen contents, or insert arbitrary text - effectively spoofing what the user believes they are seeing. For detailed technical analysis, see the Medium Article on WinRAR Vulnerability.

Detection Methods for CVE-2024-33899

Indicators of Compromise

• Archive files containing filenames with unusual byte sequences or non-printable characters (bytes in the 0x1B range indicating escape sequences)
• Terminal sessions displaying unexpected behavior when interacting with archive files
• Log entries showing extraction of files with encoded control characters in their names
• User reports of terminal corruption or unexpected screen clearing during archive operations

Detection Strategies

• Monitor for archive files with filenames containing ANSI escape sequence patterns (starting with \\x1b[ or \033[)
• Implement file integrity monitoring on systems running WinRAR to detect unusual file operations
• Deploy endpoint detection rules to identify attempts to extract archives with suspicious filename patterns
• Use SentinelOne Singularity to detect and prevent exploitation attempts through behavioral analysis of archive extraction operations

Monitoring Recommendations

• Enable verbose logging for archive operations on Linux/UNIX systems running WinRAR
• Monitor terminal emulator processes for unexpected control sequence injections
• Implement centralized log collection to correlate archive extraction events across the environment
• Set up alerts for WinRAR processes that exhibit unusual behavior patterns during file listing or extraction operations

How to Mitigate CVE-2024-33899

Immediate Actions Required

• Upgrade WinRAR to version 7.00 or later immediately on all Linux and UNIX systems
• Audit systems for WinRAR versions below 7.00 using software inventory tools
• Restrict execution of older WinRAR versions through application control policies
• Educate users about the risks of extracting archives from untrusted sources

Patch Information

RARLAB has addressed this vulnerability in WinRAR version 7.00. Organizations should update to this version or later to remediate the vulnerability. The official release notes and download are available from the RARLAB Official WinRAR Release Notes.

Workarounds

• Avoid using WinRAR to extract or list archives from untrusted sources on Linux/UNIX systems until patched
• Use alternative archive utilities that properly sanitize ANSI escape sequences in their output
• Pipe WinRAR output through a filter that strips control characters (e.g., cat -v or sed commands)
• Run WinRAR operations in non-interactive scripts that redirect output to files rather than displaying in terminals

To filter ANSI escape sequences when using vulnerable WinRAR versions, you can pipe output through a sanitization command:

# Strip ANSI escape sequences from WinRAR output
unrar l archive.rar | sed 's/\\x1b\[[0-9;]*m//g'

# Alternative using cat to display control characters visibly
unrar l archive.rar | cat -v