CVE-1999-0028 in IRIX
Summary
by MITRE
root privileges via buffer overflow in login/scheme command on sgi irix systems.
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Analysis
by VulDB Data Team • 04/16/2026
The vulnerability described in CVE-1999-0028 represents a critical buffer overflow flaw affecting SGI IRIX operating systems that allows attackers to escalate privileges to root level through the login scheme command. This issue stems from improper input validation within the authentication mechanism of IRIX systems, specifically targeting the handling of command-line arguments passed to the login scheme functionality. The vulnerability exists in the way the system processes user input when executing login commands, creating an opportunity for malicious input to overwrite adjacent memory locations beyond the intended buffer boundaries.
The technical implementation of this vulnerability involves a classic buffer overflow scenario where insufficient bounds checking allows an attacker to craft input that exceeds the allocated buffer space. When the login scheme command processes user-supplied data, it fails to properly validate the length of input parameters, enabling an attacker to overwrite critical memory segments including return addresses and control data. This memory corruption can be exploited to redirect program execution flow and ultimately gain elevated privileges. The vulnerability specifically affects the authentication subsystem of IRIX, making it particularly dangerous as it targets the core security mechanisms that protect system access.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise. An attacker exploiting this flaw can gain root access to IRIX systems without requiring valid credentials, effectively bypassing all authentication mechanisms. This represents a severe security weakness that undermines the fundamental security model of the operating system, as it allows unauthorized access to all system resources, files, and processes. The vulnerability affects systems running various versions of SGI IRIX, making it a widespread concern across organizations utilizing these legacy systems. The attack surface is particularly concerning given that the vulnerability can be exploited remotely through network-based login services, or locally through any user account with access to the login scheme functionality.
Mitigation strategies for this vulnerability require immediate patching of affected IRIX systems with security updates provided by SGI, as well as implementing comprehensive input validation measures. System administrators should disable unnecessary login scheme functionality and restrict access to privileged commands through proper access controls. The implementation of stack protection mechanisms and address space layout randomization can help reduce the exploitability of similar buffer overflow vulnerabilities. Additionally, monitoring for unusual login patterns and implementing intrusion detection systems can help identify potential exploitation attempts. Organizations should also consider migrating from legacy IRIX systems to more modern operating systems with better security implementations and ongoing vendor support. This vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of how improper input validation can lead to privilege escalation attacks that map to techniques documented in the ATT&CK framework under privilege escalation tactics.