{"id":76251,"date":"2025-09-26T11:25:17","date_gmt":"2025-09-26T11:25:17","guid":{"rendered":""},"modified":"2025-11-01T20:15:20","modified_gmt":"2025-11-02T02:15:20","slug":"cve-2025-40925-insecure-session-id-generation-in-starch-versions-0-14-and-earlier","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-40925-insecure-session-id-generation-in-starch-versions-0-14-and-earlier\/","title":{"rendered":"CVE-2025-40925: Insecure Session ID Generation in Starch Versions 0.14 and Earlier<\/strong>"},"content":{"rendered":"

Overview<\/strong><\/p>\n

The vulnerability in question, CVE-2025-40925, is a serious security issue that affects Starch versions 0.14 and earlier. Starch, a popular software, is widely used for its session management capabilities. However, the way it generates session ids in the mentioned versions is insecure and potentially harmful to systems<\/a>. This matters because session ids are critical for maintaining secure<\/a> connections between users and applications. If these ids are predictable, it could provide an attacker with unauthorized access<\/a> to systems, potentially leading to compromise or data leakage.<\/p>\n

Vulnerability Summary<\/strong><\/p>\n

CVE ID: CVE-2025-40925
\nSeverity: Critical (9.1 CVSS Score)
\nAttack Vector: Network
\nPrivileges Required: None
\nUser Interaction: None
\nImpact: Unauthorized access to systems, potential system<\/a> compromise, or data leakage<\/p>\n

Affected Products<\/strong><\/p>\n

Product | Affected Versions<\/p>\n

Starch | 0.14 and earlier<\/p>\n

How the Exploit Works<\/strong><\/p>\n

The insecure session id generation in Starch versions<\/a> 0.14 and earlier is due to a combination of factors that make the ids predictable. The default session id generator returns a SHA-1 hash seeded with a counter, the epoch time, the built-in rand function, the PID, and internal Perl reference addresses. The PID comes from a small set of numbers and the epoch time can be guessed or leaked from the HTTP Date header<\/a>. The built-in rand function, which is unsuitable for cryptographic usage, further weakens the security of the session id. An attacker could exploit this vulnerability by predicting the session id<\/a> and gaining unauthorized access to a system.<\/p>\n

Conceptual Example Code<\/strong><\/p>\n

Given the nature of this vulnerability, an exact exploit code would be complex and involve several steps, including predicting the PID, the epoch time, and the output of the rand function. However, a simplified conceptual example could be as follows:<\/p>\n

# Assume this is a part of the attacker\u2019s script\n# Predict the epoch time\nmy $predicted_epoch_time = time;\n# Predict the PID\nmy $predicted_pid = $$;\n# Simulate the rand function\nmy $predicted_rand = rand();\n# Generate the session id\nmy $session_id = sha1_hex($counter . $predicted_epoch_time . $predicted_rand . $predicted_pid . $perl_ref_addr);\n# Use the predicted session id to send a request<\/code><\/pre>\n
In a real-world scenario, the attacker would need to overcome more complexities, like guessing the Perl reference addresses and the counter. The above script is a highly simplified representation of the potential attack.<\/p>\n","protected":false},"excerpt":{"rendered":"
Overview The vulnerability in question, CVE-2025-40925, is a serious security issue that affects Starch versions 0.14 and earlier. Starch, a popular software, is widely used for its session management capabilities. However, the way it generates session ids in the mentioned versions is insecure and potentially harmful to systems. This matters because session ids are critical […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"footnotes":""},"categories":[1],"tags":[],"vendor":[],"product":[],"attack_vector":[],"asset_type":[],"severity":[],"exploit_status":[],"class_list":["post-76251","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t