CVE-2008-1687 in GNU
Summary
by MITRE
The (1) maketemp and (2) mkstemp builtin functions in GNU m4 before 1.4.11 do not quote their output when a file is created, which might allow context-dependent attackers to trigger a macro expansion, leading to unspecified use of an incorrect filename.
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Analysis
by VulDB Data Team • 07/31/2021
The vulnerability identified as CVE-2008-1687 affects the GNU m4 macro processor version 1.4.10 and earlier, specifically targeting the maketemp and mkstemp builtin functions. These functions are designed to create temporary files during macro processing, but they fail to properly quote their output when generating file paths. This fundamental flaw creates a security risk where context-dependent attackers can manipulate the macro expansion process to inject malicious code or alter the intended file creation behavior. The issue stems from insufficient output sanitization within these critical built-in functions, which are commonly used in automated build systems and configuration processes.
The technical implementation flaw occurs at the output generation level where the maketemp and mkstemp functions do not properly escape or quote the filenames they return. This allows attackers who can influence the macro processing environment to craft inputs that, when processed through these functions, result in unexpected macro expansions. The vulnerability manifests when the output of these functions is used in contexts where shell command execution or file path resolution occurs, creating opportunities for command injection or path manipulation attacks. According to CWE-78, this represents a command injection vulnerability that arises from improper handling of unquoted command arguments, while the ATT&CK framework would classify this under T1059.001 for command and scripting interpreter execution.
The operational impact of this vulnerability extends beyond simple file creation issues, as it can enable attackers to escalate privileges or compromise the build environment where GNU m4 is utilized. When these functions are employed in automated build scripts, configuration management systems, or continuous integration pipelines, an attacker who can control input to macro processing can potentially manipulate the temporary file creation process to execute arbitrary code. This risk is particularly significant in environments where m4 is used for generating configuration files, creating build scripts, or processing templates where the output is subsequently executed or interpreted. The unspecified nature of the use of incorrect filenames means that attackers can potentially cause a wide range of malicious behaviors including arbitrary file creation, execution of unintended commands, or modification of system files.
Mitigation strategies for CVE-2008-1687 focus primarily on upgrading to GNU m4 version 1.4.11 or later, where the output quoting issue has been resolved. Organizations should also implement proper input validation and sanitization for any macro processing systems that utilize these functions, particularly in environments where untrusted input might be processed. Security teams should review existing build systems and configuration management processes to identify any dependencies on vulnerable m4 versions and ensure comprehensive patching across all affected systems. Additionally, monitoring and logging should be implemented to detect anomalous file creation patterns that might indicate exploitation attempts, as the vulnerability can be leveraged to create unexpected temporary files or manipulate existing system files through the macro expansion process.