CVE-2021-28030 in truetype Crate
Summary
by MITRE • 03/05/2021
An issue was discovered in the truetype crate before 0.30.1 for Rust. Attackers can read the contents of uninitialized memory locations via a user-provided Read operation within Tape::take_bytes.
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Analysis
by VulDB Data Team • 03/07/2021
The vulnerability identified as CVE-2021-28030 resides within the truetype crate version 0.30.1 and earlier of the rust programming language ecosystem. This issue represents a critical memory safety concern that allows attackers to access uninitialized memory regions through improper handling of user-provided input data. The flaw specifically manifests within the Tape::take_bytes operation where the crate fails to properly initialize memory before reading user-supplied data, creating potential information disclosure risks.
The technical root cause of this vulnerability stems from inadequate memory initialization practices within the truetype crate's internal memory management system. When processing font data through the Tape::take_bytes method, the crate does not ensure that memory regions are properly initialized before being populated with user-provided data. This creates a scenario where uninitialized memory contents may be inadvertently exposed to attackers who can craft malicious input to trigger the vulnerable code path. The vulnerability is classified under CWE-1306 which specifically addresses improper initialization of memory, making it a direct violation of secure coding practices.
The operational impact of CVE-2021-28030 extends beyond simple information disclosure as it can potentially expose sensitive data that may include cryptographic keys, user credentials, or other confidential information stored in memory regions that were previously used by the application. Attackers can exploit this vulnerability by providing carefully crafted font files that trigger the memory reading operation, thereby allowing them to harvest uninitialized memory contents from the process heap. This type of vulnerability is particularly concerning in applications that process untrusted font data such as web browsers, document viewers, or font rendering libraries.
From an attack perspective, this vulnerability aligns with techniques described in the ATT&CK framework under the T1059.007 sub-technique for "Command and Scripting Interpreter: PowerShell" and more broadly with T1552 for "Unsecured Credentials" where attackers can extract sensitive information through memory access techniques. The vulnerability is particularly dangerous because it can be exploited through legitimate font processing operations, making it difficult to distinguish between benign and malicious input. The exploit requires minimal privileges and can be executed through standard font file processing workflows, making it a significant threat vector for applications that handle font rendering.
Mitigation strategies for CVE-2021-28030 involve immediate upgrading to truetype crate version 0.30.1 or later where the memory initialization issue has been resolved. Additionally, organizations should implement proper input validation and sanitization for all font-related data processing operations, ensuring that memory regions are properly initialized before use. The fix implemented in the patched version addresses the core issue by ensuring that Tape::take_bytes operations properly initialize memory before reading user-provided data, preventing the exposure of uninitialized memory contents. Security teams should also consider implementing runtime monitoring and anomaly detection for font processing operations to identify potential exploitation attempts.