CVE-2020-12867 in Backend
Summary
by MITRE
A NULL pointer dereference in sanei_epson_net_read in SANE Backends through 1.0.29 allows a malicious device connected to the same local network as the victim to cause a denial of service, aka GHSL-2020-075.
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Analysis
by VulDB Data Team • 10/21/2020
The vulnerability CVE-2020-12867 represents a critical NULL pointer dereference flaw within the SANE (Scanner Access Now Easy) backends library version 1.0.29 and earlier. This issue specifically affects the sanei_epson_net_read function which handles network communication with Epson scanner devices. The vulnerability arises from insufficient input validation and error handling within the network scanning protocol implementation, creating a scenario where a malicious device on the same local network can exploit this weakness to disrupt normal operations.
The technical flaw manifests when a malicious device sends crafted network packets to a victim system running SANE backends. The sanei_epson_net_read function fails to properly validate incoming network data structures before attempting to dereference pointers that may remain NULL due to malformed packet construction. This NULL pointer dereference results in an immediate crash of the scanning daemon or application process, effectively causing a denial of service condition that prevents legitimate users from accessing scanner functionality. The vulnerability is particularly dangerous because it requires no special privileges or authentication to exploit, as it operates at the network level within the local network segment.
Operationally, this vulnerability presents a significant risk to environments where SANE backends are deployed for network scanning operations, particularly in office environments, educational institutions, or any setting where multiple devices share the same local network. Attackers can leverage this weakness to disrupt document management workflows, prevent legitimate scanning operations, or create persistent service interruptions. The impact extends beyond simple denial of service as it can affect business continuity and productivity when critical scanning operations are interrupted. The vulnerability's exploitation is relatively straightforward since it only requires network access to the victim's local network segment, making it accessible to attackers who can establish a malicious presence on the same network.
Mitigation strategies should focus on immediate patching of SANE backends to version 1.0.30 or later where this vulnerability has been addressed through proper NULL pointer validation and input sanitization. Network segmentation and firewall rules can provide temporary protection by restricting network access to scanning services, while implementing network monitoring can help detect anomalous scanning traffic patterns. Organizations should also consider disabling unnecessary network scanning capabilities when not actively required. This vulnerability aligns with CWE-476 which catalogs NULL pointer dereference issues, and represents a typical example of how network protocol implementations can create exploitable conditions. The ATT&CK framework categorizes this under privilege escalation and denial of service techniques, specifically targeting system services and network protocols to disrupt legitimate operations. Regular security assessments of network scanning infrastructure and maintaining updated software versions remain essential defensive measures against similar vulnerabilities in network-based services.