CVE-2016-2842 in Android
Summary
by MITRE
The doapr_outch function in crypto/bio/b_print.c in OpenSSL 1.0.1 before 1.0.1s and 1.0.2 before 1.0.2g does not verify that a certain memory allocation succeeds, which allows remote attackers to cause a denial of service (out-of-bounds write or memory consumption) or possibly have unspecified other impact via a long string, as demonstrated by a large amount of ASN.1 data, a different vulnerability than CVE-2016-0799.
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Analysis
by VulDB Data Team • 09/12/2022
The vulnerability identified as CVE-2016-2842 represents a critical memory management flaw within the OpenSSL cryptographic library affecting versions 1.0.1 through 1.0.1s and 1.0.2 through 1.0.2g. This issue resides in the doapr_outch function located within the crypto/bio/b_print.c source file, where the implementation fails to properly validate memory allocation outcomes before proceeding with subsequent operations. The absence of allocation verification creates a pathway for malicious actors to exploit the library's handling of extended string inputs, particularly those encountered in ASN.1 data processing. This flaw operates under the weakness classification of CWE-704, which encompasses improper handling of memory allocation failures, and aligns with ATT&CK technique T1499.004 for denial of service through resource exhaustion. The vulnerability manifests when the library encounters unusually long strings during ASN.1 data processing, potentially triggering out-of-bounds write operations or excessive memory consumption patterns that can destabilize the application or system.
The operational impact of CVE-2016-2842 extends beyond simple denial of service scenarios, as the memory allocation failure can lead to unpredictable system behavior and potential exploitation for more sophisticated attacks. When remote attackers supply malformed or excessively long ASN.1 data structures to vulnerable OpenSSL implementations, the library's inability to properly handle allocation failures can result in memory corruption that may allow for arbitrary code execution or complete system compromise. The vulnerability's exploitation requires the attacker to have the capability to send crafted ASN.1 data to a vulnerable service, making it particularly dangerous in network-facing applications such as web servers, email servers, or any system utilizing OpenSSL for secure communications. The flaw's relationship to CVE-2016-0799 demonstrates the complexity of OpenSSL's memory handling issues, where multiple vulnerabilities in the same codebase can present similar exploitation patterns but require distinct mitigation approaches. The lack of proper error handling in the doapr_outch function creates a cascade effect where a simple allocation failure can propagate through the system, potentially leading to system crashes, memory exhaustion, or in worst-case scenarios, code execution.
Mitigation strategies for CVE-2016-2842 primarily focus on immediate version upgrades to patched OpenSSL releases, specifically 1.0.1s and 1.0.2g, which contain the necessary memory allocation verification checks. System administrators should prioritize patching all affected OpenSSL installations, particularly those running in production environments where exposure to malicious input is possible. Additional protective measures include implementing input validation mechanisms at application layers to filter out unusually long strings before they reach the OpenSSL library, deploying network intrusion detection systems to monitor for suspicious ASN.1 data patterns, and establishing robust memory monitoring to detect potential exploitation attempts. Organizations should also consider implementing application firewalls or web application firewalls that can detect and block malicious ASN.1 data sequences, while maintaining comprehensive logging of all SSL/TLS connections for forensic analysis. The remediation process must include thorough testing of patched environments to ensure that the memory allocation fixes do not introduce performance regressions or compatibility issues with existing applications. Security teams should also conduct vulnerability assessments to identify all systems utilizing vulnerable OpenSSL versions and establish automated patch management processes to prevent similar issues from arising in the future. The vulnerability serves as a reminder of the critical importance of proper error handling in cryptographic libraries and the potential for seemingly minor memory management issues to create significant security risks in widely deployed software components.