CVE-2011-1400 in tex-common
Summary
by MITRE
The default configuration of the shell_escape_commands directive in conf/texmf.d/95NonPath.cnf in the tex-common package before 2.08.1 in Debian GNU/Linux squeeze, Ubuntu 10.10 and 10.04 LTS, and possibly other operating systems lists certain programs, which might allow remote attackers to execute arbitrary code via a crafted TeX document.
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Analysis
by VulDB Data Team • 10/21/2021
The vulnerability identified as CVE-2011-1400 resides within the tex-common package configuration files of Debian and Ubuntu operating systems, specifically in the shell_escape_commands directive located at conf/texmf.d/95NonPath.cnf. This flaw represents a critical security oversight in how TeX document processing handles external command execution, creating a potential remote code execution vector through crafted TeX documents. The vulnerability affects Debian GNU/Linux squeeze and Ubuntu versions 10.04 LTS and 10.10, with similar issues potentially present in other operating systems using the same package versions.
The technical flaw stems from an insecure default configuration where the shell_escape_commands directive includes a list of programs that should be permitted to execute shell commands when processing TeX documents. This configuration allows for the execution of arbitrary commands through the shell_escape feature, which is designed to enable TeX to execute external programs during document compilation. When attackers craft malicious TeX documents that leverage this feature, they can exploit the default configuration to execute arbitrary code on systems running affected versions of the tex-common package. The vulnerability is classified under CWE-78 as a failure to properly sanitize command arguments, creating an environment where untrusted input can directly translate into system command execution.
The operational impact of this vulnerability is significant as it allows remote attackers to execute arbitrary code on affected systems without requiring local privileges. An attacker could craft a malicious TeX document that, when processed by a vulnerable system, would execute commands with the privileges of the user running the TeX processing application. This could lead to complete system compromise, data exfiltration, or the establishment of persistent backdoors. The vulnerability is particularly dangerous in environments where users might receive TeX documents from untrusted sources, such as email attachments or web-based document sharing platforms. The attack vector is remote and can be executed through the normal document processing workflow, making it difficult to detect and prevent without proper configuration management.
Mitigation strategies for CVE-2011-1400 involve several approaches that align with standard security practices and ATT&CK framework principles. System administrators should immediately update to tex-common version 2.08.1 or later, which addresses this vulnerability through proper configuration of the shell_escape_commands directive. Additionally, organizations should implement proper access controls and privilege separation when processing untrusted TeX documents, ensuring that document processing occurs with minimal privileges. The configuration should explicitly disable shell_escape functionality for untrusted documents or implement strict whitelisting of permitted external commands. Network segmentation and monitoring of document processing activities can help detect potential exploitation attempts. This vulnerability demonstrates the importance of secure configuration management and the principle of least privilege, as outlined in the ATT&CK technique T1059 for command and scripting interpreter usage, where the vulnerability enables attackers to leverage system command execution capabilities through legitimate software features.