CVE-2021-21047 in Photoshop
Summary
by MITRE • 02/12/2021
Adobe Photoshop versions 21.2.4 (and earlier) and 22.1.1 (and earlier) are affected by an Out-of-bounds Write vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.
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Analysis
by VulDB Data Team • 02/28/2021
Adobe Photoshop contains a critical out-of-bounds write vulnerability that affects versions 21.2.4 and earlier, as well as 22.1.1 and earlier. This flaw resides in the application's handling of malformed image files and represents a significant security risk that could be exploited by remote attackers. The vulnerability stems from insufficient bounds checking when processing specific file formats, particularly those involving image metadata or embedded data structures. When a user opens a maliciously crafted file, the application fails to properly validate array indices or buffer limits, leading to memory corruption that can be leveraged for arbitrary code execution. The attack requires user interaction since the exploit is triggered during the file opening process, making it a classic social engineering target that could be delivered through phishing campaigns or malicious file sharing. This vulnerability aligns with CWE-787, which describes out-of-bounds write conditions in software applications, and represents a serious threat to user security since successful exploitation would allow attackers to execute malicious code with the privileges of the current user. The impact extends beyond simple code execution as it could potentially enable privilege escalation or lateral movement within a network environment. Security researchers have identified that this vulnerability could be exploited through various file formats including but not limited to psd, psb, and other image containers that Photoshop supports. The flaw demonstrates a fundamental weakness in input validation and memory management practices within Adobe's image processing libraries. Organizations using these affected versions of Photoshop should immediately implement mitigations including restricting user access to potentially malicious files, deploying network-based intrusion detection systems, and ensuring timely patch deployment. This vulnerability also maps to ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation would likely involve executing malicious payloads through the Photoshop application. The risk assessment indicates this vulnerability should be prioritized for immediate remediation due to its remote exploitability and potential for widespread impact across creative professionals who frequently handle external image files. Adobe has addressed this issue in subsequent releases, and users should upgrade to versions that contain the appropriate security patches to eliminate the risk of exploitation.
The technical nature of this vulnerability involves memory corruption that occurs when Photoshop attempts to write data beyond the allocated memory boundaries of an array or buffer. This particular flaw manifests during the parsing of image file headers or metadata sections where the application does not properly validate the length or structure of incoming data. Attackers can craft malicious files that contain specially constructed data sequences designed to trigger the out-of-bounds write condition, causing the application to overwrite adjacent memory locations. The consequences of such memory corruption can be severe as it may allow attackers to overwrite critical program variables, function pointers, or return addresses within the application's execution stack. This type of vulnerability is particularly dangerous because it can be exploited to bypass modern security mitigations including address space layout randomization and data execution prevention mechanisms. The exploitation process typically involves careful crafting of the malicious file to ensure that the out-of-bounds write overwrites specific memory locations in a controlled manner that ultimately leads to code execution. Security professionals should note that this vulnerability represents a classic example of how improper input validation can lead to severe remote code execution risks in multimedia applications. The attack vector is particularly concerning because Photoshop is widely used in creative industries and often processes files from untrusted sources, making it an attractive target for threat actors seeking to compromise creative workflows. Organizations should implement comprehensive security measures including application whitelisting, regular security updates, and user education about the risks of opening untrusted files. The vulnerability's classification as a remote code execution threat means that it could be exploited through automated attack vectors without requiring physical access to target systems. This makes it particularly dangerous in enterprise environments where Photoshop is widely deployed and used by multiple users across different departments.
Mitigation strategies for this vulnerability should include immediate patching of all affected Adobe Photoshop installations to ensure that the underlying memory corruption issue is resolved. System administrators should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation attempts. The use of application sandboxing or virtualization technologies can provide additional protection layers that limit the damage that could occur if an attacker successfully exploits this vulnerability. Security monitoring should be enhanced to detect unusual file opening patterns or attempts to access suspicious file types through Photoshop. Organizations should also conduct regular vulnerability assessments to identify any other potentially affected software components within their environment that might share similar memory handling vulnerabilities. The remediation process should include comprehensive testing of patched versions to ensure that security updates do not introduce compatibility issues with existing workflows or file processing capabilities. Regular security awareness training for users should emphasize the importance of not opening suspicious files or attachments that could contain malicious payloads designed to exploit this vulnerability. Additionally, organizations should establish incident response procedures that specifically address potential exploitation attempts targeting this type of vulnerability, including forensic analysis capabilities to investigate potential breaches. The implementation of automated patch management systems can help ensure that all affected systems receive security updates in a timely manner, reducing the window of opportunity for attackers to exploit this vulnerability. Given the widespread use of Photoshop in creative and media environments, coordinated remediation efforts across multiple departments and user groups are essential to achieve comprehensive protection against this threat.