Rejetto HTTP File Server (HFS) 2.3x Remote Code Execution (RCE) Vulnerability Analysis and Mitigation Guide (CVE-2014-6287)
Executive & SecOps Summary
SECOPS ASSESSMENTRejetto HTTP File Server (HFS) 2.3x versions prior to 2.3c
Unauthenticated remote attackers can execute arbitrary system commands and gain full control of the host by sending crafted HTTP requests
Immediately upgrade to a patched version (2.3c or later) or decommission the legacy HFS service in favor of secure alternatives
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Because Rejetto HFS 2.3x is legacy software, the strongly recommended action is to migrate to a modern, actively supported file-sharing platform. If migration is not immediately feasible, upgrade the HFS binary to version 2.3c or later.
# 1. Identify and terminate the running HFS process (Windows environment)
taskkill /F /IM hfs.exe
# 2. Backup and isolate the vulnerable binary
rename C:\HFS\hfs.exe hfs_vulnerable_backup.exe.bak
# 3. Download the secure version (2.3c or later) from the official Rejetto repository and replace the binary2. Temporary Workaround & Hardening Configuration
If patching cannot be performed immediately, deploy a Web Application Firewall (WAF) or a reverse proxy to block malicious null-byte and macro execution patterns.
# Example Nginx reverse proxy configuration to block malicious HFS payloads
server {
listen 80;
server_name hfs.local;
location / {
# Block requests containing null bytes (%00) or HFS macro execution patterns
if ($request_uri ~* "(%00|\{\x2eexec|\{\x2esystem)") {
return 403;
}
proxy_pass http://127.0.0.1:8080;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
}
}3. Log Audit & IoC Verification Commands
Inspect the HFS access logs for the presence of null bytes (%00) and macro execution syntax to identify potential compromise attempts.
# PowerShell script to scan HFS log files for indicators of compromise (IoCs)
$LogPath = 'C:\HFS\logs\*.txt'
if (Test-Path $LogPath) {
Select-String -Path $LogPath -Pattern '%00', '\{\..*\}' |
Select-Object LineNumber, Line, Path |
Format-Table -AutoSize
} else {
Write-Host 'HFS log path not found. Please verify the actual log directory.' -ForegroundColor Yellow
}Block Exploits Instantly with Managed Virtual Patching Rules
Can't patch production immediately? Deploy managed WAF rules at the edge to intercept RCE, SQLi, and deserialization payloads before they hit your origin server.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2014-6287) exists in the findMacroMarker function within parserLib.pas of Rejetto HTTP File Server (HFS) 2.3x. The root cause is improper input validation when handling search parameters containing null byte (%00) sequences. HFS utilizes a custom template and macro parsing engine to handle dynamic requests; however, the injection of a null byte causes the parser to misinterpret string boundaries, bypassing macro execution restrictions and leading to arbitrary code execution (CWE-94).
2. Exploitation Mechanics & Attack Scenario
An attacker crafts an HTTP GET request containing a null byte (%00) followed by an HFS macro command (such as {.exec|....}) within the search query parameter (e.g., ?search=%00{.exec|cmd.exe /c ....}). When the findMacroMarker function processes this input, the null byte prematurely terminates or bypasses the standard validation checks, allowing the subsequent macro command to be passed directly to the execution engine. This allows remote attackers to spawn system shells (e.g., via PowerShell or cmd.exe) and establish reverse connections to their command-and-control (C2) servers.
3. Infrastructure & Business Impact
With a CVSS 3.1 score of 9.8 (Critical) and its inclusion in the CISA KEV (Known Exploited Vulnerabilities) catalog, this vulnerability represents an extreme risk with active in-the-wild exploitation. The EPSS score of 0.9932 highlights a near-certain probability of exploitation attempts against exposed instances. Successful exploitation grants the attacker the privileges of the HFS process, typically leading to full system compromise, data exfiltration, ransomware deployment, and lateral movement within the internal network.
Official Vendor Advisories & References
The findMacroMarker function in parserLib.pas in Rejetto HTTP File Server (aks HFS or HttpFileServer) 2.3x before 2.3c allows remote attackers to execute arbitrary programs via a %00 sequence in a search action.
Frequently Asked SecOps Questions (CVE-2014-6287)
FAQQ1. How critical is CVE-2014-6287 and is it actively exploited in the wild?
CVE-2014-6287 is rated CVSS 9.8 (CRITICAL) with a 30-day EPSS exploitation probability of 99.3%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2014-6287?
Primary impacted vendors include rejetto across http_file_server. Scope summary: Rejetto HTTP File Server (HFS) 2.3x versions prior to 2.3c
Q3. What temporary mitigations or workarounds exist for CVE-2014-6287 before patching?
[Mitigation] Immediately upgrade to a patched version (2.3c or later) or decommission the legacy HFS service in favor of secure alternatives Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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