CVE-2015-0843: Critical Buffer Overflow Vulnerability in Yubiserver Before Version 0.6

Overview

In the realm of cybersecurity, one cannot underestimate the importance of staying updated with the latest vulnerabilities. One such critical security flaw that requires immediate attention is CVE-2015-0843, a buffer overflow vulnerability in yubiserver before version 0.6. This vulnerability, with a high CVSS severity score of 9.8, poses a significant threat to all systems running a version of yubiserver prior to 0.6. If successfully exploited, this vulnerability could lead to system compromise and potential data leakage, causing substantial damage to the affected parties.

Vulnerability Summary

CVE ID: CVE-2015-0843
Severity: Critical (9.8)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise and data leakage

Affected Products

Product | Affected Versions

yubiserver | Versions prior to 0.6

How the Exploit Works

The vulnerability CVE-2015-0843 is a buffer overflow vulnerability caused by the incorrect usage of the sprintf function in yubiserver before 0.6. In essence, sprintf writes data into a buffer without checking if the buffer can hold the data. If the data is larger than the buffer, it will overflow into adjacent memory, overwriting whatever was there. An attacker can exploit this to execute arbitrary code or disrupt the normal functioning of the system, possibly leading to system compromise or data leakage.

Conceptual Example Code

Here is a conceptual example of how an attacker might exploit the vulnerability. The attacker sends a specially crafted payload that causes buffer overflow when processed by the vulnerable yubiserver function.

#include <string.h>
int main() {
char buffer[500];
char payload[1000];
// Fill payload with a large amount of data
memset(payload, 'A', sizeof(payload)-1);
payload[sizeof(payload)-1] = '\0';
// Simulate the misuse of sprintf
sprintf(buffer, "%s", payload);
return 0;
}

This code overflows the buffer with ‘A’ characters, leading to a buffer overflow. In real-world scenarios, an attacker would replace the ‘A’ characters with malicious code, potentially leading to system compromise.