CVE-2011-1213 in Lotus Notes
Summary
by MITRE
Integer underflow in lzhsr.dll in Autonomy KeyView, as used in IBM Lotus Notes before 8.5.2 FP3, allows remote attackers to execute arbitrary code via a crafted header in a .lzh attachment that triggers a stack-based buffer overflow, aka SPR PRAD88MJ2W.
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Analysis
by VulDB Data Team • 06/02/2025
The vulnerability identified as CVE-2011-1213 represents a critical security flaw in Autonomy KeyView's lzhsr.dll component, which was widely integrated into IBM Lotus Notes before version 8.5.2 Fix Pack 3. This integer underflow condition occurs when processing .lzh file attachments, creating a scenario where maliciously crafted headers can trigger a stack-based buffer overflow. The flaw stems from improper input validation and arithmetic handling within the decompression routine, specifically when the software attempts to calculate buffer sizes based on malformed header values. The vulnerability falls under the CWE-190 category of Integer Overflow or Wraparound, which is a well-documented weakness that frequently leads to buffer overflow conditions. The attack vector requires remote exploitation through email attachments, making it particularly dangerous in enterprise environments where Lotus Notes is extensively used for business communication. When a user opens a maliciously crafted .lzh file, the integer underflow causes the software to allocate insufficient buffer space, leading to memory corruption that can be exploited to execute arbitrary code with the privileges of the affected application. This vulnerability directly maps to ATT&CK technique T1203 by enabling initial access through malicious email attachments, while also supporting T1059 for command execution within the compromised system. The impact extends beyond individual user compromise to potentially affect entire enterprise networks, as Lotus Notes is commonly used for internal communications and document sharing. The flaw demonstrates how legacy software components can harbor critical vulnerabilities that persist across multiple versions, particularly when third-party libraries like Autonomy KeyView are integrated without proper security auditing. Organizations using older versions of IBM Lotus Notes face significant risk exposure, as the vulnerability can be exploited without user interaction beyond opening the malicious attachment, making it a prime target for phishing campaigns and targeted attacks. The integer underflow condition creates a predictable pattern of memory corruption that attackers can leverage to overwrite critical program execution pointers or return addresses, effectively allowing remote code execution in the context of the running Lotus Notes process. The vulnerability's classification as remote code execution through a stack-based buffer overflow aligns with common exploitation patterns documented in security research, where malformed input triggers memory corruption that can be controlled to redirect program flow. Security researchers have noted that such vulnerabilities often require minimal exploit development effort due to the predictable nature of the memory corruption, making them particularly attractive to threat actors. The remediation approach centers on applying the official IBM fix pack 8.5.2 FP3 or later, which includes updated Autonomy KeyView components with proper integer overflow checks and input validation. Organizations should also implement email filtering measures and user education to reduce the likelihood of successful exploitation, while considering network segmentation to limit potential lateral movement if compromise occurs. The vulnerability serves as a reminder of the importance of maintaining up-to-date third-party components and conducting regular security assessments of integrated software libraries, particularly those handling file processing and decompression functions.