CVE-2007-4622 in AIX
Summary
by MITRE
Integer underflow in the dns_name_fromtext function in (1) libdns_nonsecure.a and (2) libdns_secure.a in IBM AIX 5.2 allows local users to gain privileges via a crafted "-y" (TSIG key) command line argument to dig.
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Analysis
by VulDB Data Team • 08/23/2019
The vulnerability identified as CVE-2007-4622 represents a critical integer underflow flaw within the IBM AIX 5.2 DNS resolution libraries, specifically affecting the dns_name_fromtext function in both libdns_nonsecure.a and libdns_secure.a components. This issue arises from improper input validation when processing command line arguments, particularly the "-y" flag used for TSIG key specification in the dig utility. The integer underflow occurs when the function processes malformed TSIG key arguments, leading to unpredictable memory behavior and potential privilege escalation opportunities for local attackers. This vulnerability falls under the CWE-190 category of integer overflow/underflow, specifically manifesting as an underflow condition that can corrupt memory structures and potentially allow malicious code execution. The flaw is particularly dangerous because it operates within the core DNS resolution libraries that are fundamental to system networking operations, making it a prime target for exploitation by adversaries seeking to elevate their privileges within the AIX environment.
The technical exploitation of this vulnerability hinges on the manipulation of the TSIG key command line argument to the dig utility, where the integer underflow in the dns_name_fromtext function creates a condition where an attacker can craft a malicious input that causes the integer value to wrap around to a much smaller value than expected. This underflow condition can result in buffer overread or overwrite scenarios within the DNS library's memory management routines, potentially allowing an attacker to manipulate memory pointers or overwrite critical data structures. The vulnerability is classified under the ATT&CK technique T1068 for locally executed code and T1548.001 for privilege escalation through legitimate system tools. When a local user executes the dig command with a specially crafted TSIG key argument, the system's DNS resolution process becomes compromised, creating opportunities for privilege escalation attacks that can potentially elevate the user's access level from standard user to root or administrative privileges.
The operational impact of CVE-2007-4622 extends beyond simple privilege escalation, as it affects the fundamental DNS resolution capabilities of IBM AIX 5.2 systems, potentially disrupting network services and creating security gaps that could be leveraged in broader attack scenarios. The vulnerability affects systems running IBM AIX 5.2 where the dig utility is present and accessible to local users, making it particularly concerning for enterprise environments where multiple users may have access to system tools. The exploitation of this vulnerability can lead to complete system compromise, allowing attackers to execute arbitrary code with elevated privileges, access sensitive system information, and potentially establish persistent access to the compromised system. Organizations running affected versions of IBM AIX 5.2 should consider this vulnerability as a high-priority threat due to its potential for privilege escalation and the critical nature of DNS services within enterprise networks. The vulnerability demonstrates the importance of proper input validation in system libraries and highlights the need for robust memory safety practices in security-critical components, particularly those handling network protocol data. Remediation efforts should focus on updating to patched versions of IBM AIX or implementing workarounds that prevent execution of the vulnerable dig command with malicious TSIG key arguments.
The underlying cause of this vulnerability stems from insufficient bounds checking and input validation within the DNS library functions, where the integer underflow condition is not properly handled during the processing of TSIG key data structures. This type of vulnerability represents a classic example of how seemingly minor flaws in memory management can have catastrophic security implications, particularly in system-level libraries that are widely used and trusted by operating system components. The vulnerability's classification under CWE-190 emphasizes the need for developers to implement proper integer overflow and underflow protections in security-sensitive code paths, particularly those handling user-provided input data. From an ATT&CK perspective, this vulnerability aligns with techniques for privilege escalation through legitimate system tools and can be used as part of broader attack chains targeting system integrity and access control mechanisms. The impact on system security is amplified by the fact that the dig utility is commonly used for network diagnostics and troubleshooting, making it an attractive target for exploitation by threat actors seeking to maintain persistent access to compromised systems.