CVE-2017-8818 in cURL
Summary
by MITRE
curl and libcurl before 7.57.0 on 32-bit platforms allow attackers to cause a denial of service (out-of-bounds access and application crash) or possibly have unspecified other impact because too little memory is allocated for interfacing to an SSL library.
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Analysis
by VulDB Data Team • 01/25/2021
The vulnerability identified as CVE-2017-8818 represents a critical memory allocation flaw affecting curl and libcurl versions prior to 7.57.0 on 32-bit platforms. This issue stems from insufficient memory allocation during the interaction with SSL libraries, creating a fundamental security weakness that can be exploited by malicious actors. The vulnerability specifically targets 32-bit systems where memory constraints are more pronounced, making the impact more severe compared to 64-bit environments where memory addressing capabilities are greater. The flaw manifests when the application attempts to interface with SSL libraries, leading to improper memory handling that can result in buffer overflows or underflows.
The technical implementation of this vulnerability involves the curl library's memory management routines during SSL handshake and data transmission processes. When processing SSL connections on 32-bit architectures, the library allocates memory based on assumptions that do not account for the actual memory requirements of certain SSL operations. This miscalculation creates a scenario where subsequent memory access operations can traverse beyond allocated boundaries, resulting in out-of-bounds memory access patterns. The vulnerability is categorized under CWE-122 as "Heap-based Buffer Overflow" and also relates to CWE-787 "Out-of-bounds Read" and CWE-788 "Out-of-bounds Write" within the Common Weakness Enumeration framework. The flaw demonstrates characteristics consistent with memory safety issues that are commonly exploited in remote code execution and denial of service attacks.
The operational impact of CVE-2017-8818 extends beyond simple application crashes, potentially enabling more sophisticated attack vectors that can compromise system availability and integrity. An attacker exploiting this vulnerability can cause applications using affected curl versions to crash, leading to denial of service conditions that disrupt legitimate user access to services. The unspecified other impacts mentioned in the vulnerability description suggest potential for more serious consequences including information disclosure or privilege escalation, particularly when the vulnerable applications are used in server environments or critical infrastructure. The vulnerability affects any system that relies on curl or libcurl for SSL/TLS operations, including web servers, application servers, and network monitoring tools that depend on these libraries for secure communications.
Organizations utilizing affected curl versions should implement immediate mitigation strategies to address this vulnerability. The primary recommendation involves upgrading to curl and libcurl version 7.57.0 or later, which includes proper memory allocation handling for SSL library interfaces. System administrators should conduct comprehensive vulnerability assessments to identify all instances of affected software across their infrastructure, paying particular attention to 32-bit systems where the risk is highest. Additionally, implementing network segmentation and access controls can help limit the potential attack surface, while monitoring systems should be configured to detect unusual application behavior or crash patterns that may indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1499.004 "Endpoint Denial of Service" and may also map to T1071.004 "Application Layer Protocol: DNS" when exploited through DNS resolution failures, making it a significant concern for enterprise security operations centers that must address both immediate remediation needs and long-term security posture improvements.