CVE-2018-20221 in Ajera Timesheets
Summary
by MITRE
Secure/SAService.rem in Deltek Ajera Timesheets 9.10.16 and prior are vulnerable to remote code execution via deserialization of untrusted user input from an authenticated user. The executed code will run as the IIS Application Pool that is running the application.
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Analysis
by VulDB Data Team • 11/01/2025
The vulnerability identified as CVE-2018-20221 affects Deltek Ajera Timesheets version 9.10.16 and earlier, specifically targeting the Secure/SAService.rem component. This represents a critical remote code execution flaw that can be exploited by authenticated users to gain arbitrary code execution on the target system. The vulnerability stems from improper input validation during the deserialization process, allowing maliciously crafted data to be executed within the application's context. The attack vector requires an authenticated user session, but once exploited, the malicious code executes with the privileges of the IIS Application Pool running the application, potentially providing attackers with significant system access and control.
The technical flaw manifests in the insecure deserialization of user-provided data within the SOAP web service endpoint. When legitimate users submit data through the Secure/SAService.rem interface, the application fails to properly validate or sanitize the incoming serialized objects before processing them. This vulnerability aligns with CWE-502 which specifically addresses deserialization of untrusted data as a weakness that can lead to remote code execution. The flaw enables attackers to craft malicious payloads that, when processed by the vulnerable application, trigger arbitrary code execution. The deserialization process typically involves converting serialized data structures back into executable objects, and when this process occurs without proper validation, it creates an attack surface where malicious input can be transformed into executable instructions.
The operational impact of this vulnerability is severe and multifaceted. Attackers who successfully exploit this vulnerability can execute code with the privileges of the IIS Application Pool, which typically runs with elevated permissions and may have access to sensitive data, network resources, and system functionalities. This could result in data breaches, system compromise, and potential lateral movement within the network. The vulnerability affects organizations using Deltek Ajera Timesheets in production environments where the application is accessible over the network and where user authentication is required. The attack requires only an authenticated user session, which means that even if network access is restricted, internal threats or compromised accounts could still exploit this vulnerability. The execution of code with application pool privileges can lead to complete system compromise, data exfiltration, and potential establishment of persistent backdoors.
Organizations should implement immediate mitigations including applying the vendor-provided patches and updates for Deltek Ajera Timesheets to address this vulnerability. Additionally, network segmentation should be implemented to limit access to the vulnerable application to only authorized personnel and systems. Security monitoring should be enhanced to detect suspicious deserialization activities and unusual code execution patterns. Access controls should be reviewed and strengthened to ensure that only necessary users have access to the vulnerable service endpoints. The mitigation strategies should align with ATT&CK technique T1059.007 which covers command and scripting interpreter for remote code execution. Organizations should also consider implementing application whitelisting policies to prevent unauthorized code execution and deploy intrusion detection systems to monitor for exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify similar vulnerabilities in other applications and systems within the organization's infrastructure.