CVE-2024-0727 in OpenSSL
Summary
by MITRE • 01/26/2024
Issue summary: Processing a maliciously formatted PKCS12 file may lead OpenSSL to crash leading to a potential Denial of Service attack Impact summary: Applications loading files in the PKCS12 format from untrusted sources might terminate abruptly. A file in PKCS12 format can contain certificates and keys and may come from an untrusted source. The PKCS12 specification allows certain fields to be NULL, but OpenSSL does not correctly check for this case. This can lead to a NULL pointer dereference that results in OpenSSL crashing. If an application processes PKCS12 files from an untrusted source using the OpenSSL APIs then that application will be vulnerable to this issue. OpenSSL APIs that are vulnerable to this are: PKCS12_parse(), PKCS12_unpack_p7data(), PKCS12_unpack_p7encdata(), PKCS12_unpack_authsafes() and PKCS12_newpass(). We have also fixed a similar issue in SMIME_write_PKCS7(). However since this function is related to writing data we do not consider it security significant. The FIPS modules in 3.2, 3.1 and 3.0 are not affected by this issue.
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Analysis
by VulDB Data Team • 10/31/2024
The vulnerability identified as CVE-2024-0727 represents a critical denial of service weakness within OpenSSL's handling of PKCS12 formatted files. This flaw specifically targets the processing of maliciously crafted PKCS12 containers that can contain certificates and cryptographic keys obtained from untrusted sources. The issue stems from OpenSSL's inadequate validation of NULL field conditions within PKCS12 structures, creating a scenario where applications relying on OpenSSL APIs for PKCS12 file processing become susceptible to abrupt termination. The vulnerability operates through a NULL pointer dereference mechanism that directly causes OpenSSL to crash, effectively disrupting service availability for legitimate users.
The technical implementation of this vulnerability aligns with CWE-476, which categorizes NULL pointer dereference conditions as a fundamental programming error that can lead to system instability. When applications invoke the vulnerable OpenSSL functions including PKCS12_parse(), PKCS12_unpack_p7data(), PKCS12_unpack_p7encdata(), PKCS12_unpack_authsafes(), and PKCS12_newpass(), they encounter memory access violations that result in immediate program termination. The attack vector is particularly concerning because PKCS12 files are commonly used for certificate distribution and key management in enterprise environments, making them frequent targets for malicious actors seeking to disrupt services. This vulnerability demonstrates the importance of proper input validation and error handling in cryptographic libraries that process structured data formats.
From an operational perspective, the impact extends beyond simple service disruption to potentially compromising the reliability of systems that depend on OpenSSL for secure communications. The vulnerability affects a broad range of applications including web servers, email systems, and certificate management tools that utilize OpenSSL's PKCS12 processing capabilities. Security practitioners must consider this weakness within the context of the ATT&CK framework's privilege escalation and denial of service tactics, as attackers could leverage this flaw to systematically target services that process untrusted certificate data. The fact that the FIPS modules in versions 3.2, 3.1, and 3.0 remain unaffected provides some mitigation options for organizations requiring FIPS compliance, though this does not address the broader ecosystem of vulnerable OpenSSL installations.
The remediation strategy requires immediate patching of affected OpenSSL versions and implementation of proper input validation measures within applications that process PKCS12 files. Organizations should prioritize updating their OpenSSL installations to versions containing the fix, while also implementing defensive programming practices such as validating all input data before processing and incorporating proper error handling mechanisms. Additionally, security teams should monitor for potential exploitation attempts targeting this vulnerability through network traffic analysis and application logs, as the crash behavior may be observable during active attacks. The vulnerability serves as a reminder of the critical importance of thorough validation of structured data inputs in cryptographic libraries, particularly those handling certificate formats that are integral to secure communications infrastructure.