CVE-2017-7716 in radare2
Summary
by MITRE
The read_u32_leb128 function in libr/util/uleb128.c in radare2 1.3.0 allows remote attackers to cause a denial of service (heap-based buffer over-read and application crash) via a crafted Web Assembly file.
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Analysis
by VulDB Data Team • 11/29/2022
The vulnerability identified as CVE-2017-7716 resides within the radare2 reverse engineering framework version 1.3.0, specifically in the libr/util/uleb128.c component that handles unsigned leb128 decoding operations. This flaw manifests when processing Web Assembly files, which employ leb128 encoding for various data structures including function signatures, local variables, and other metadata. The read_u32_leb128 function fails to properly validate the boundaries of input data during leb128 decoding, creating a condition where maliciously crafted Web Assembly files can trigger improper memory access patterns.
The technical implementation of this vulnerability stems from inadequate bounds checking within the leb128 decoding logic. When the function processes a crafted Web Assembly file, it attempts to read unsigned 32-bit values encoded using the leb128 format without sufficient validation of the input buffer boundaries. This allows an attacker to construct a Web Assembly file containing malformed leb128 sequences that cause the decoder to read beyond allocated memory regions, resulting in a heap-based buffer over-read condition. The vulnerability operates at the intersection of software parsing and memory management, where the expected behavior of leb128 decoding is subverted through carefully constructed input data that exploits the lack of proper input sanitization.
The operational impact of this vulnerability extends beyond simple denial of service, as it represents a critical security flaw that can be exploited remotely by attackers. When an application processes a malicious Web Assembly file through radare2, the heap-based buffer over-read causes the application to crash or behave unpredictably, effectively creating a denial of service condition that can be leveraged by attackers to disrupt legitimate operations. This vulnerability particularly affects environments where radare2 is used for analyzing Web Assembly files, such as security research platforms, automated malware analysis systems, or any application that incorporates radare2 for binary analysis. The flaw demonstrates how seemingly benign parsing operations can become attack vectors when proper input validation is absent, making it a prime example of how insufficient boundary checking can lead to remote exploitation.
Mitigation strategies for CVE-2017-7716 require immediate patching of affected radare2 installations to version 1.3.1 or later, which contains the necessary fixes for the leb128 decoding routine. Organizations should also implement defensive measures such as input validation for Web Assembly files, sandboxing analysis environments, and network segmentation to limit the potential impact of exploitation attempts. The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and relates to ATT&CK technique T1059.007 for execution through web-based applications. Additionally, implementing proper bounds checking mechanisms and adopting secure coding practices for parsing operations can prevent similar vulnerabilities from emerging in other software components that handle similar encoding formats. The fix typically involves adding explicit boundary validation checks before any memory reads occur during leb128 decoding operations, ensuring that input data cannot cause buffer over-read conditions.