CVE-2018-4038 in Word Processor
Summary
by MITRE
An exploitable arbitrary write vulnerability exists in the open document format parser of the Atlantis Word Processor, version 3.2.7.2, while trying to null-terminate a string. A specially crafted document can allow an attacker to pass an untrusted value as a length to a constructor. This constructor will miscalculate a length and then use it to calculate the position to write a null byte. This can allow an attacker to corrupt memory, which can result in code execution under the context of the application. An attacker must convince a victim to open a specially crafted document in order to trigger this vulnerability.
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Analysis
by VulDB Data Team • 06/12/2023
The vulnerability identified as CVE-2018-4038 represents a critical arbitrary write flaw within the Atlantis Word Processor version 3.2.7.2 that specifically targets the Open Document Format parser component. This weakness stems from improper handling of string termination operations during document parsing, creating a scenario where malicious input can manipulate memory layout through a flawed length calculation mechanism. The vulnerability exists in the context of document processing where the application attempts to null-terminate strings while parsing open document format files, making it particularly dangerous for end users who may encounter crafted malicious documents in normal workflow scenarios.
The technical implementation of this vulnerability manifests through a specific flaw in how the application handles memory allocation and string manipulation during the parsing process. When the parser encounters certain document structures, it accepts an untrusted length value from the input document and passes this value directly to a constructor function. This constructor performs a miscalculation of the actual required buffer size, leading to an incorrect determination of the memory location where a null byte should be written. The flaw is classified as a buffer overflow condition where the calculated write position exceeds the intended boundaries, resulting in memory corruption that can be leveraged for arbitrary code execution. This type of vulnerability aligns with CWE-787: "Out-of-bounds Write" and falls under the broader category of memory corruption vulnerabilities that are frequently exploited in software exploitation frameworks.
The operational impact of CVE-2018-4038 extends beyond simple document corruption, as successful exploitation can result in complete system compromise when the application executes code under its current privilege context. Attackers can craft malicious documents that, when opened by victims, trigger the memory corruption sequence and potentially execute arbitrary code with the privileges of the Atlantis Word Processor application. This creates a significant risk for enterprise environments where users may inadvertently open compromised documents, particularly in phishing scenarios or when receiving documents from untrusted sources. The vulnerability's exploitation requires social engineering to convince victims to open malicious documents, but once triggered, it can provide attackers with persistent access to the target system. The attack pattern follows typical exploit chains documented in MITRE ATT&CK framework under techniques such as T1203: "Exploitation for Client Execution" and T1059: "Command and Scripting Interpreter" where initial access leads to code execution within the application's memory space.
Mitigation strategies for CVE-2018-4038 should focus on both immediate defensive measures and long-term architectural improvements. Users should immediately update to the latest version of Atlantis Word Processor where this vulnerability has been patched, as the vendor has released remediation updates addressing the buffer handling issues. Organizations should implement document sanitization policies that scan and validate all incoming documents before processing, particularly for email attachments and file transfers from external sources. Network-level controls such as email filtering and web application firewalls can help prevent the delivery of malicious documents to end users. Additionally, application hardening techniques including stack canaries, address space layout randomization, and data execution prevention should be enabled to make exploitation more difficult even if the vulnerability is present. System administrators should also monitor for suspicious document opening activities and implement user education programs to reduce the success rate of social engineering attacks that leverage this vulnerability. The fix typically involves proper input validation and bounds checking in the string parsing functions to prevent the propagation of untrusted length values to memory allocation constructors.