CVE-2011-2502 in systemtap
Summary
by MITRE
runtime/staprun/staprun_funcs.c in the systemtap runtime tool (staprun) in SystemTap before 1.6 does not properly validate modules when a module path is specified by a user for user-space probing, which allows local users in the stapusr group to gain privileges via a crafted module in the search path in the -u argument.
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Analysis
by VulDB Data Team • 12/07/2021
The vulnerability identified as CVE-2011-2502 affects the systemtap runtime tool known as staprun, which is part of the SystemTap profiling and debugging infrastructure used primarily in linux environments. This flaw exists within the runtime component's staprun_funcs.c file and specifically impacts versions of SystemTap prior to 1.6. The vulnerability stems from insufficient validation mechanisms within the staprun utility when processing user-space module paths, creating a privilege escalation vector that can be exploited by local users who belong to the stapusr group. This group is typically created during SystemTap installation to allow non-root users to perform system-level profiling operations while maintaining appropriate security boundaries.
The technical flaw manifests when the staprun utility processes module paths specified through the -u command line argument. The system fails to properly validate or sanitize the module paths provided by users, allowing malicious actors to manipulate the module loading process through carefully crafted module files placed in the search path. This improper validation creates a path traversal or module injection vulnerability where an attacker can specify a module path that points to a maliciously crafted module file, bypassing normal security checks and access controls. The vulnerability is particularly concerning because it operates at the runtime level, meaning it can be exploited without requiring elevated privileges initially, but can ultimately allow privilege escalation to root or other high-privilege levels.
The operational impact of this vulnerability is significant for systems running affected versions of SystemTap, particularly those where users have been granted membership in the stapusr group. Local users who are part of this group can leverage this vulnerability to execute arbitrary code with elevated privileges, potentially compromising the entire system. The attack requires the user to have legitimate access to the stapusr group, which is typically granted to users who need to perform system profiling activities. However, the vulnerability allows these users to escalate their privileges beyond what should be permitted by the group membership. This creates a serious security risk for environments where SystemTap is used for system monitoring and where user access controls may not be properly enforced.
The vulnerability aligns with CWE-22 Path Traversal and CWE-78 Improper Neutralization of Special Elements in Output Used by a Downstream Component, representing a classic privilege escalation vector through improper input validation. From an ATT&CK perspective, this maps to privilege escalation techniques using legitimate system tools and can be categorized under T1068 Valid Accounts and T1548.1 Account Manipulation. The attack chain typically involves an attacker with stapusr group membership placing a malicious module in a location that will be processed by staprun, then executing the staprun command with the crafted module path to achieve privilege escalation. Organizations should implement immediate mitigations including upgrading to SystemTap version 1.6 or later, reviewing and restricting stapusr group membership, and implementing proper module path validation controls to prevent unauthorized module loading.
Mitigation strategies should focus on both immediate remediation and long-term security hardening. The primary recommendation is to upgrade to SystemTap version 1.6 or newer, which includes the necessary patches to address the improper module validation issue. Additionally, administrators should audit and restrict membership in the stapusr group, ensuring that only trusted users have access to system profiling capabilities. Network segmentation and privilege separation should be implemented to limit the potential impact of successful exploitation. SystemTap configuration should be reviewed to minimize the exposure of user-space probing capabilities, and proper file system permissions should be enforced to prevent unauthorized module creation or modification in system directories. Regular security auditing of systemtap installations and monitoring for suspicious staprun usage patterns should be implemented as part of ongoing security operations.