Source: cve@mitre.org
The PKI functionality in Mac OS X 10.2.8 and 10.3.2 allows remote attackers to cause a denial of service (service crash) via malformed ASN.1 sequences.
Mac OS X versions 10.2.8 and 10.3.2 are vulnerable to a denial-of-service (DoS) attack due to a flaw in their Public Key Infrastructure (PKI) implementation. Attackers can remotely crash the system by sending specially crafted, malformed ASN.1 sequences, rendering the affected system unavailable.
Step 1: Payload Delivery: The attacker crafts a malicious ASN.1 sequence. This sequence is designed to be malformed or contain unexpected data structures that the PKI component cannot handle correctly.
Step 2: ASN.1 Parsing: The victim's Mac OS X system receives the malicious ASN.1 sequence, likely through a network connection or a file import operation that triggers the PKI functionality.
Step 3: Vulnerability Trigger: The PKI component attempts to parse the malformed ASN.1 data. Due to the lack of proper input validation, the parsing process encounters an error, such as an invalid data structure or an out-of-bounds memory access.
Step 4: Service Crash: The error during parsing leads to a service crash. This could manifest as a segmentation fault, an unhandled exception, or a similar system-level error, resulting in the termination of the PKI service or the entire operating system, causing a denial of service.
The vulnerability stems from inadequate input validation within the PKI component's ASN.1 parsing routines. Specifically, the software fails to properly handle malformed ASN.1 sequences, leading to a service crash. The root cause is likely an unhandled exception or an attempt to access memory outside of allocated bounds when processing the malformed data. This could manifest as an integer overflow, a buffer overflow, or a similar memory-related error during the parsing process. The lack of robust error handling allows the crafted input to trigger the crash, causing a DoS.
Due to the age of the vulnerability, specific APT groups are unlikely to be actively targeting it. However, any threat actor with the capability to craft ASN.1 sequences could potentially exploit this vulnerability. CISA KEV status: Not Listed
Network traffic analysis: Examine network traffic for ASN.1 sequences, especially those associated with PKI operations (e.g., SSL/TLS handshakes, certificate validation). Look for unusual or malformed sequences.
System logs: Review system logs (e.g., system.log, crash logs) for errors related to PKI components, ASN.1 parsing, or unexpected service crashes.
Forensic analysis: Examine memory dumps or core files for evidence of memory corruption or crashes related to PKI processes.
IDS/IPS signatures: Implement signatures to detect malformed ASN.1 sequences, although this is challenging without specific exploit details.
Upgrade: Upgrade to a patched version of Mac OS X. This is the primary and most effective remediation step. Since the affected versions are very old, this is likely a migration to a supported OS.
Network segmentation: Isolate systems running vulnerable versions from untrusted networks to limit exposure.
Input validation: Implement robust input validation at the network perimeter to filter out malformed ASN.1 sequences before they reach the vulnerable systems. This is difficult without specific exploit details.
Intrusion Detection/Prevention: Deploy an IDS/IPS with signatures that can detect and block malicious ASN.1 sequences. This is challenging without specific exploit details.
Monitor: Continuously monitor system logs and network traffic for suspicious activity related to PKI functions.