CVE-2021-28792 in Swift Development Environment Extension
Summary
by MITRE • 03/19/2021
The unofficial Swift Development Environment extension before 2.12.1 for Visual Studio Code allows remote attackers to execute arbitrary code by constructing a malicious workspace with a crafted sourcekit-lsp.serverPath, swift.languageServerPath, swift.path.sourcekite, swift.path.sourcekiteDockerMode, swift.path.swift_driver_bin, or swift.path.shell configuration value that triggers execution upon opening the workspace.
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Analysis
by VulDB Data Team • 04/03/2021
The vulnerability identified as CVE-2021-28792 affects the unofficial Swift Development Environment extension for Visual Studio Code, specifically versions prior to 2.12.1. This represents a critical security flaw that enables remote attackers to achieve arbitrary code execution through deliberate manipulation of workspace configuration parameters. The vulnerability stems from insufficient input validation and sanitization within the extension's handling of Swift development environment settings, creating a pathway for malicious actors to inject and execute unauthorized commands on affected systems.
The technical implementation of this vulnerability involves the manipulation of several specific configuration parameters within the VS Code workspace settings. Attackers can craft malicious values for serverPath, languageServerPath, sourcekite, sourcekiteDockerMode, swift_driver_bin, or shell configuration fields that, when processed by the extension upon workspace opening, trigger unintended execution sequences. These configuration values are typically used to specify paths to Swift development tools and language servers, but the extension fails to properly validate or sanitize these inputs before use. The flaw operates at the configuration parsing level where user-supplied paths are directly executed without proper security checks, creating a command injection vulnerability that aligns with CWE-78 and CWE-94 categories.
From an operational perspective, this vulnerability presents a severe risk to developers working in environments where they might unknowingly open malicious workspaces or where attackers can influence workspace contents through supply chain attacks. The attack requires minimal privileges to execute successfully since the malicious code runs within the context of the VS Code process, which typically has sufficient permissions to execute system commands. The impact extends beyond individual developer machines to potentially compromise entire development environments, especially in corporate settings where multiple developers might share workspace configurations or where automated deployment processes could be exploited. This vulnerability directly maps to ATT&CK technique T1059.001 for command and scripting interpreter execution and T1566 for credential access through supply chain compromise.
The exploitation scenario involves attackers crafting malicious workspace files containing crafted configuration values that, when opened in VS Code with the vulnerable extension installed, trigger code execution. The vulnerability affects the sourcekit-lsp and Swift language server components that are integral to Swift development environments, making it particularly dangerous for Swift developers who rely heavily on these tools. The lack of proper input validation means that attackers can specify arbitrary paths that will be executed as system commands, potentially allowing for privilege escalation, data exfiltration, or further compromise of the development environment. Organizations should consider this vulnerability as part of a broader attack surface that includes development tools and IDE extensions, which are often overlooked in traditional security assessments.
Mitigation strategies should focus on immediate patching to version 2.12.1 or later where the vulnerability has been addressed through proper input validation and sanitization of configuration parameters. System administrators should implement strict access controls for workspace files and development environments, ensuring that only trusted sources can provide workspace configurations. Additional protective measures include monitoring for suspicious configuration changes, implementing network segmentation for development environments, and conducting regular security assessments of development tools and extensions. Organizations should also consider implementing automated tools to scan for vulnerable extensions and maintain updated inventories of installed development tools to prevent exploitation of similar vulnerabilities in other components of their development infrastructure. The fix implemented by the extension developers addresses the root cause by ensuring that all user-provided path configurations undergo proper validation before being processed, thereby preventing the execution of malicious code through crafted workspace parameters.