CVE-2017-9998 in libdwarf
Summary
by MITRE
The _dwarf_decode_s_leb128_chk function in dwarf_leb.c in libdwarf through 2017-06-28 allows remote attackers to cause a denial of service (Segmentation fault) via a crafted file.
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Analysis
by VulDB Data Team • 12/30/2020
The vulnerability identified as CVE-2017-9998 resides within the libdwarf library, a critical component used for parsing and processing debug information in binary files. This library serves as a foundational element for various security tools, debugging utilities, and system analysis software that rely on accurate interpretation of debug data. The specific flaw is located in the _dwarf_decode_s_leb128_chk function within the dwarf_leb.c source file, which handles the decoding of signed leb128 encoded values commonly found in debug information formats. The vulnerability represents a classic buffer over-read condition that occurs when processing malformed input data, specifically crafted files designed to exploit the library's parsing routines.
The technical implementation of this vulnerability stems from inadequate input validation within the leb128 decoding mechanism. When the _dwarf_decode_s_leb128_chk function processes a specially crafted file containing malformed leb128 encoded data, it fails to properly bounds-check the input stream before attempting to read beyond the allocated buffer boundaries. This flaw falls under the CWE-129 weakness category, which encompasses issues related to improper validation of array indices and buffer overflows. The function's failure to validate input parameters results in a segmentation fault when the program attempts to access memory locations that are outside the expected bounds of the data structure being processed. This particular implementation vulnerability affects all versions of libdwarf released prior to June 28, 2017, making it a significant concern for systems that depend on this library for debug information processing.
The operational impact of CVE-2017-9998 extends beyond simple denial of service, as it can be leveraged by remote attackers to disrupt system availability and potentially compromise the stability of applications that utilize libdwarf. When exploited, this vulnerability can cause segmentation faults that result in application crashes, forcing system administrators to restart services and potentially leading to extended downtime. The attack vector is particularly concerning because it requires no special privileges or access to the target system, as attackers can simply craft malicious files and distribute them for processing. This makes the vulnerability applicable across numerous attack scenarios where debug information files are processed automatically, including software build systems, security scanning tools, and forensic analysis platforms. The vulnerability's classification under ATT&CK technique T1499.004 highlights its potential for causing denial of service through system resource consumption and process termination.
Mitigation strategies for CVE-2017-9998 primarily focus on updating to patched versions of libdwarf where the input validation has been strengthened to prevent buffer over-read conditions. System administrators should immediately upgrade to libdwarf version 2017-06-28 or later, which includes proper bounds checking and input validation within the _dwarf_decode_s_leb128_chk function. Additionally, implementing proper input sanitization measures and validating all debug information files before processing can serve as intermediate protective measures. Organizations should also consider deploying intrusion detection systems that can identify attempts to process suspicious debug files and establish network segmentation to limit the impact of potential exploitation. The vulnerability's remediation aligns with security best practices outlined in NIST SP 800-53 and ISO 27001 frameworks, emphasizing the importance of maintaining up-to-date software components and implementing proper input validation controls. Regular security assessments and vulnerability scanning should be conducted to identify other potentially vulnerable components within the software ecosystem that may share similar architectural weaknesses.