CVE-2018-12976 in Go Doc Dot Org
Summary
by MITRE
In Go Doc Dot Org (gddo) through 2018-06-27, an attacker could use specially crafted <go-import> tags in packages being fetched by gddo to cause a directory traversal and remote code execution.
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Analysis
by VulDB Data Team • 04/03/2023
The vulnerability CVE-2018-12976 represents a critical security flaw in the Go Doc Dot Org (gddo) documentation server that was prevalent through the 2018-06-27 release. This issue stems from improper handling of <go-import> tags during package fetching operations, creating a pathway for remote attackers to execute arbitrary code on affected systems. The vulnerability specifically targets the gddo server's processing of Go package metadata, which is essential for the go toolchain's dependency resolution and documentation retrieval mechanisms.
The technical flaw manifests when gddo processes package information containing maliciously crafted <go-import> tags that include directory traversal sequences. These tags are typically used by the go toolchain to specify import paths and repository locations for Go packages. When gddo fetches and parses these tags without adequate sanitization, it allows attackers to manipulate the path resolution logic to traverse directories outside the intended package boundaries. This directory traversal capability directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as directory traversal or path traversal vulnerabilities.
The operational impact of this vulnerability is severe as it enables remote code execution on systems running vulnerable gddo instances. Attackers can leverage this flaw to execute arbitrary commands with the privileges of the gddo service account, potentially leading to complete system compromise. The vulnerability affects not only the targeted gddo server but also any system that relies on it for package documentation and metadata retrieval. Given that gddo serves as a primary documentation source for Go packages, the attack surface extends to any environment where developers depend on Go's package ecosystem, including development workstations, continuous integration servers, and production environments that fetch documentation from vulnerable instances.
The attack vector for CVE-2018-12976 operates through the standard Go toolchain workflow where developers or automated systems request package information from gddo. When a malicious package contains specially crafted <go-import> tags, the gddo server processes these tags without proper validation, allowing the attacker to manipulate the file system access patterns. This vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter: PowerShell and T1203 for Exploitation for Client Execution, as it enables attackers to execute commands on compromised systems. Organizations using gddo for package documentation and dependency management face significant risk, particularly those with automated build processes that fetch package metadata from external sources. The vulnerability demonstrates the critical importance of input validation and proper path handling in web applications that process user-provided metadata, especially in environments where such metadata is used to resolve and access file system resources.
Mitigation strategies for CVE-2018-12976 include immediate patching of gddo instances to versions that properly sanitize <go-import> tags and implement proper path validation. Organizations should also consider implementing network segmentation to isolate gddo servers from critical systems and establish strict access controls for package metadata retrieval. Additionally, monitoring and logging of package fetch operations can help detect anomalous behavior indicative of exploitation attempts. The fix typically involves implementing proper input validation, sanitization of path components, and restricting file system access to predefined safe directories. Security teams should also review and update their incident response procedures to address potential exploitation of this vulnerability in their Go development environments, ensuring that all systems relying on gddo for package documentation are properly secured against directory traversal attacks.