CVE-2011-2660 in Linux Enterprise Desktop
Summary
by MITRE
The modify_resolvconf_suse script in the vpnc package before 0.5.1-55.10.1 in SUSE Linux Enterprise Desktop 11 SP1 might allow remote attackers to execute arbitrary commands via a crafted DNS domain name.
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Analysis
by VulDB Data Team • 11/18/2021
The vulnerability identified as CVE-2011-2660 resides within the modify_resolvconf_suse script component of the vpnc package, which serves as a crucial element for managing DNS resolution configuration in SUSE Linux Enterprise Desktop 11 SP1 systems. This particular flaw represents a command injection vulnerability that arises from inadequate input validation within the script's handling of DNS domain names. The vpnc package functions as a client for Cisco Virtual Private Network connections, and during the establishment of such connections, it processes DNS domain information that gets incorporated into system configuration files. The vulnerability specifically manifests when the script fails to properly sanitize or escape special characters in DNS domain names, creating an opportunity for malicious input to be interpreted as shell commands rather than mere domain identifiers.
The technical exploitation of this vulnerability occurs through the manipulation of DNS domain names that contain shell metacharacters such as semicolons, ampersands, or backticks, which are then executed by the script during the resolution configuration process. When a remote attacker crafts a malicious DNS domain name containing these special characters, the modify_resolvconf_suse script processes this input without proper sanitization, leading to arbitrary command execution with the privileges of the user running the vpnc client. This represents a classic command injection flaw that aligns with CWE-77 and CWE-88 categories, where user-supplied data is directly incorporated into shell commands without adequate validation or escaping mechanisms. The vulnerability's impact is particularly concerning because it allows remote attackers to execute commands on the target system without requiring authentication, making it a significant security risk in environments where vpnc is used for remote network access.
The operational impact of CVE-2011-2660 extends beyond simple privilege escalation to encompass full system compromise capabilities for attackers who can influence DNS resolution during VPN connections. An attacker who controls a DNS server or can manipulate DNS responses can craft malicious domain names that, when processed by the vulnerable vpnc script, result in arbitrary code execution on the target system. This vulnerability directly maps to ATT&CK technique T1059.001 for command and scripting interpreter, as it enables the execution of arbitrary commands through shell injection. The implications are particularly severe in enterprise environments where SUSE Linux Enterprise Desktop systems may be used for remote access, as attackers could potentially establish persistent access, escalate privileges, or exfiltrate sensitive data through this attack vector. The vulnerability's remote nature means that exploitation does not require physical access to the system, making it particularly dangerous for organizations relying on VPN connectivity for secure remote access.
Mitigation strategies for CVE-2011-2660 should focus on immediate patching of the vpnc package to version 0.5.1-55.10.1 or later, which includes proper input sanitization and escaping mechanisms. Organizations should also implement network-level controls to monitor and restrict DNS traffic to prevent manipulation of DNS resolution during VPN connections. Additional defensive measures include disabling unnecessary VPN features that process external DNS information, implementing strict input validation for all user-supplied data, and monitoring system logs for suspicious command execution patterns. The vulnerability demonstrates the importance of input validation in security-critical scripts and serves as a reminder of the potential for command injection flaws in network configuration utilities. System administrators should also consider implementing principle of least privilege for vpnc execution, ensuring that the script runs with minimal required privileges to reduce potential impact from successful exploitation attempts.