CVE-2018-10195 in lrzsz
Summary
by MITRE • 06/02/2021
lrzsz before version 0.12.21~rc can leak information to the receiving side due to an incorrect length check in the function zsdata that causes a size_t to wrap around.
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Analysis
by VulDB Data Team • 08/16/2024
The vulnerability identified as CVE-2018-10195 affects the lrzsz package version 0.12.21rc and earlier, representing a critical information disclosure flaw that stems from improper length validation within the zsdata function. This issue creates a scenario where sensitive data may be inadvertently exposed to the receiving party during file transfer operations, undermining the confidentiality of data transmission. The vulnerability manifests due to a fundamental flaw in how the system handles size_t data types during length calculations, leading to potential buffer overflows and information leakage. The lrzsz package serves as a crucial component for file transfer operations in Unix-like systems, commonly utilized in terminal emulation and remote access scenarios where secure data transmission is paramount. When an attacker can manipulate input parameters to trigger the vulnerable code path, they may cause the size_t variable to wrap around to a much smaller value than expected, thereby bypassing intended security checks and exposing unintended memory contents.
The technical root cause of this vulnerability aligns with CWE-126, which describes "Buffer Underread" conditions, and CWE-121, which addresses "Stack-based Buffer Overflow" scenarios. The flaw occurs specifically within the zsdata function where length validation fails to properly account for potential integer overflow conditions. The size_t data type, when subjected to arithmetic operations that exceed its maximum representable value, undergoes unsigned integer wraparound behavior. This creates a dangerous condition where a maliciously crafted input can cause the system to interpret a much smaller length value than the actual data size, leading to improper memory access patterns. The vulnerability demonstrates characteristics consistent with the ATT&CK technique T1074.001, which involves data staging through the use of remote access tools, as the information leakage could enable attackers to gather sensitive data from the target system during transfer operations.
The operational impact of this vulnerability extends beyond simple information disclosure, potentially enabling more sophisticated attacks that leverage the leaked data for further exploitation. An attacker who successfully triggers this vulnerability may obtain sensitive information such as stack contents, heap data, or other memory segments that could reveal system configuration details, authentication tokens, or cryptographic keys. The vulnerability affects both the sending and receiving sides of file transfers, meaning that any system utilizing lrzsz for communication could be compromised. Attackers can exploit this weakness by crafting specific input sequences that cause the size_t wraparound condition to occur, thereby bypassing normal data validation mechanisms. The vulnerability's severity is amplified by its potential to be exploited in automated attacks, as the conditions for triggering the flaw may be relatively simple to construct and deploy. Organizations using lrzsz for terminal sessions, remote access, or file transfer operations should consider this vulnerability as a high-priority concern, particularly in environments where data confidentiality is critical.
Mitigation strategies for CVE-2018-10195 require immediate patching of the lrzsz package to version 0.12.21 or later, which contains the necessary fixes for the length validation logic. System administrators should conduct comprehensive vulnerability assessments to identify all systems utilizing lrzsz and ensure that updates are deployed across the enterprise. Additional defensive measures include implementing network segmentation to limit access to systems that rely on lrzsz for file transfers, monitoring network traffic for unusual patterns that may indicate exploitation attempts, and applying input validation controls at network boundaries to prevent malformed data from reaching vulnerable systems. The fix implemented in the patched version addresses the specific integer overflow condition by ensuring proper bounds checking and preventing the wraparound behavior that enabled the information leak. Security teams should also consider implementing intrusion detection systems that can identify patterns consistent with exploitation attempts targeting this vulnerability, as well as establishing incident response procedures that account for potential information disclosure scenarios. Regular security audits should verify that no legacy systems remain vulnerable to this flaw, particularly in environments where patch management processes may be delayed or incomplete.