CVE-2011-2207 in dirmngr
Summary
by MITRE
dirmngr before 2.1.0 improperly handles certain system calls, which allows remote attackers to cause a denial of service (DOS) via a specially-crafted certificate.
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Analysis
by VulDB Data Team • 11/28/2019
The vulnerability identified as CVE-2011-2207 affects dirmngr versions prior to 2.1.0, representing a critical denial of service weakness that stems from improper handling of specific system calls within the OpenPGP key management system. This flaw exists within the directory manager component that facilitates certificate distribution and key server communication for the GNU Privacy Guard suite, making it a significant concern for systems relying on secure key management infrastructure. The vulnerability operates through a carefully crafted certificate that triggers unexpected behavior in the system call processing mechanism, ultimately leading to system instability and service disruption.
The technical implementation of this vulnerability involves dirmngr's insufficient validation and handling of certain system calls when processing maliciously constructed certificates. When the system encounters these specially crafted certificates, the improper system call handling causes the process to enter an undefined state or crash, resulting in complete service unavailability. This behavior aligns with CWE-248, which addresses improper exception handling, and demonstrates how flawed system call management can lead to denial of service conditions. The vulnerability specifically targets the certificate processing pipeline within dirmngr, where the application fails to properly sanitize or validate certificate data before attempting system-level operations.
From an operational perspective, this vulnerability presents a serious threat to organizations relying on OpenPGP key management systems, particularly those using older versions of GnuPG that incorporate affected dirmngr components. Attackers can exploit this weakness remotely by simply presenting a malicious certificate to a vulnerable system, causing the dirmngr service to crash and effectively denying legitimate users access to key management services. The impact extends beyond simple service interruption as it can compromise the availability of cryptographic infrastructure critical for secure communications, email encryption, and digital signatures within enterprise environments. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under the denial of service category, specifically targeting system availability through process termination.
Mitigation strategies for CVE-2011-2207 require immediate patching of affected systems to upgrade dirmngr to version 2.1.0 or later, which includes proper system call handling and certificate validation mechanisms. Organizations should implement network monitoring to detect unusual certificate processing patterns that might indicate exploitation attempts, while also establishing robust patch management procedures to prevent similar vulnerabilities from arising in other components of their cryptographic infrastructure. Additionally, system administrators should consider implementing certificate validation policies that limit the scope of certificates accepted by dirmngr and maintain regular security assessments of their OpenPGP key management systems. The fix addresses the underlying flaw by implementing proper error handling for system calls and strengthening certificate validation routines to prevent malformed data from triggering system crashes, thereby aligning with security best practices outlined in industry standards for cryptographic system maintenance and vulnerability remediation.