CVE-2020-24972 in Kleopatra
Summary
by MITRE
The Kleopatra component before 3.1.12 (and before 20.07.80) for GnuPG allows remote attackers to execute arbitrary code because openpgp4fpr: URLs are supported without safe handling of command-line options. The Qt platformpluginpath command-line option can be used to load an arbitrary DLL.
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Analysis
by VulDB Data Team • 11/11/2020
The vulnerability identified as CVE-2020-24972 affects the Kleopatra component within GnuPG, a widely used open-source implementation of the OpenPGP standard for email encryption and digital signatures. This security flaw exists in versions prior to 3.1.12 and 20.07.80, representing a critical weakness that enables remote code execution through improper handling of OpenPGP fingerprint URLs. The vulnerability stems from the insecure processing of openpgp4fpr: URLs which are used to reference OpenPGP keys through their fingerprint identifiers, a common method for key exchange and verification in cryptographic communications.
The technical exploitation mechanism involves the Qt platformpluginpath command-line option which can be manipulated through the URL scheme to load arbitrary dynamic link libraries. This occurs because the Kleopatra application fails to properly sanitize or validate command-line parameters when processing these specific URL formats, allowing attackers to inject malicious DLL loading commands. The vulnerability specifically targets the Qt framework's plugin loading mechanism, which is commonly used for graphical user interface components and can be leveraged to execute arbitrary code with the privileges of the affected application. This represents a classic command injection flaw that has been classified under CWE-78 as improper neutralization of special elements used in OS commands.
The operational impact of this vulnerability is severe as it allows remote attackers to achieve arbitrary code execution without requiring any authentication or prior access to the target system. An attacker could craft malicious OpenPGP fingerprint URLs that, when opened by an affected Kleopatra instance, would load and execute malicious code on the victim's machine. This could lead to complete system compromise, data exfiltration, or the installation of additional malware. The vulnerability is particularly dangerous because it can be triggered through normal email interactions or key exchange processes where users might unknowingly click on malicious links, making it a significant threat vector in phishing attacks and social engineering campaigns.
Mitigation strategies should focus on immediate patching of affected versions to 3.1.12 or 20.07.80, which contain proper input validation and URL handling mechanisms. Organizations should also implement network-level protections such as URL filtering and content inspection to block suspicious openpgp4fpr: URLs. Security teams should monitor for potential exploitation attempts and consider implementing application whitelisting policies to prevent unauthorized DLL loading. From an ATT&CK framework perspective, this vulnerability maps to T1059.001 for command and script interpreter execution and T1566 for phishing techniques, as it enables attackers to bypass traditional security controls through seemingly legitimate cryptographic operations. System administrators should also consider disabling the affected URL scheme processing entirely if the functionality is not required in their environment, and maintain regular updates to ensure protection against similar vulnerabilities in other components of the GnuPG ecosystem.