CVE-2020-19909 in cURL
Summary
by MITRE • 08/22/2023
Integer overflow vulnerability in tool_operate.c in curl 7.65.2 via crafted value as the retry delay.
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Analysis
by VulDB Data Team • 07/08/2024
The integer overflow vulnerability identified as CVE-2020-19909 resides within the curl library's tool_operate.c component and represents a critical security flaw affecting version 7.65.2. This vulnerability stems from improper handling of retry delay values during network operations, creating a scenario where maliciously crafted input can trigger unexpected behavior in the underlying integer arithmetic. The flaw specifically manifests when the tool processes retry delay parameters, which are used to determine wait times between connection attempts during failed network operations.
The technical implementation of this vulnerability involves integer overflow conditions that occur when the retry delay value exceeds the maximum representable value for the integer type used in the calculation. This overflow results in the delay value wrapping around to a negative or extremely small positive number, which can cause the application to behave unpredictably during retry logic execution. The vulnerability is particularly concerning because it can be triggered through user-controlled input during network operations, potentially allowing attackers to manipulate the retry behavior of curl applications.
From an operational perspective, this vulnerability creates significant risks for systems that rely on curl for network communications, particularly those that process untrusted input or operate in environments where network reliability is crucial. When exploited, the integer overflow can cause the application to enter infinite loops, consume excessive system resources, or potentially execute arbitrary code depending on how the overflow affects subsequent operations. The impact extends beyond simple denial of service scenarios, as the overflow can disrupt normal application flow and potentially provide attackers with opportunities to escalate privileges or bypass security controls.
The vulnerability aligns with CWE-190, which specifically addresses integer overflow conditions, and represents a classic example of improper integer handling in network applications. From an ATT&CK framework perspective, this vulnerability could be leveraged as part of a broader attack chain, potentially serving as an initial access vector or as a means to establish persistence through manipulated retry mechanisms. Organizations utilizing curl for automated network operations, web scraping, or API communications should be particularly concerned about this vulnerability, as it can be exploited to disrupt services or create covert channels through manipulated retry behaviors.
Mitigation strategies should focus on immediate patching of curl to versions that address the integer overflow in tool_operate.c, while also implementing input validation controls that limit retry delay values to reasonable ranges. Network administrators should monitor for unusual retry patterns or resource consumption spikes that might indicate exploitation attempts. Additionally, organizations should consider implementing application-level controls that sanitize all retry delay parameters before processing, and establish network monitoring procedures that can detect anomalous retry behavior patterns. The vulnerability underscores the importance of proper integer overflow protection in network libraries and the need for comprehensive security testing of all input handling mechanisms in network applications.