Siemens SIMATIC S7-1500 Improper Input Validation (CVE-2025-38400)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(505276);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/03/24");

  script_cve_id("CVE-2025-38400");

  script_name(english:"Siemens SIMATIC S7-1500 Improper Input Validation (CVE-2025-38400)");

  script_set_attribute(attribute:"synopsis", value:
"The remote OT asset is affected by a vulnerability.");
  script_set_attribute(attribute:"description", value:
"In the Linux kernel, the following vulnerability has been resolved:
nfs: Clean up /proc/net/rpc/nfs when nfs_fs_proc_net_init() fails.
syzbot reported a warning below [1] following a fault injection in
nfs_fs_proc_net_init(). [0]    When nfs_fs_proc_net_init() fails,
/proc/net/rpc/nfs is not removed.    Later, rpc_proc_exit() tries to
remove /proc/net/rpc, and the warning  is logged as the directory is
not empty.    Let's handle the error of nfs_fs_proc_net_init()
properly.    [0]:  FAULT_INJECTION: forcing a failure.  name failslab,
interval 1, probability 0, space 0, times 0  CPU: 1 UID: 0 PID: 6120
Comm: syz.2.27 Not tainted 6.16.0-rc1-syzkaller-00010-g2c4a1f3fe03e #0
PREEMPT(full)  Hardware name: Google Google Compute Engine/Google
Compute Engine, BIOS Google 05/07/2025  Call Trace:   <TASK>
dump_stack_lvl (lib/dump_stack.c:123)   should_fail_ex (lib/fault-
inject.c:73 lib/fault-inject.c:174)   should_failslab
(mm/failslab.c:46)   kmem_cache_alloc_noprof (mm/slub.c:4178
mm/slub.c:4204)   __proc_create (fs/proc/generic.c:427)
proc_create_reg (fs/proc/generic.c:554)   proc_create_net_data
(fs/proc/proc_net.c:120)   nfs_fs_proc_net_init (fs/nfs/client.c:1409)
nfs_net_init (fs/nfs/inode.c:2600)   ops_init
(net/core/net_namespace.c:138)   setup_net
(net/core/net_namespace.c:443)   copy_net_ns
(net/core/net_namespace.c:576)   create_new_namespaces
(kernel/nsproxy.c:110)   unshare_nsproxy_namespaces
(kernel/nsproxy.c:218 (discriminator 4))   ksys_unshare
(kernel/fork.c:3123)   __x64_sys_unshare (kernel/fork.c:3190)
do_syscall_64 (arch/x86/entry/syscall_64.c:63
arch/x86/entry/syscall_64.c:94)   entry_SYSCALL_64_after_hwframe
(arch/x86/entry/entry_64.S:130)   </TASK>    [1]:  remove_proc_entry:
removing non-empty directory 'net/rpc', leaking at least 'nfs'
WARNING: CPU: 1 PID: 6120 at fs/proc/generic.c:727
remove_proc_entry+0x45e/0x530 fs/proc/generic.c:727  Modules linked
in:  CPU: 1 UID: 0 PID: 6120 Comm: syz.2.27 Not tainted
6.16.0-rc1-syzkaller-00010-g2c4a1f3fe03e #0 PREEMPT(full)  Hardware
name: Google Google Compute Engine/Google Compute Engine, BIOS Google
05/07/2025   RIP: 0010:remove_proc_entry+0x45e/0x530
fs/proc/generic.c:727  Code: 3c 02 00 0f 85 85 00 00 00 48 8b 93 d8 00
00 00 4d 89 f0 4c 89 e9 48 c7 c6 40 ba a2 8b 48 c7 c7 60 b9 a2 8b e8
33 81 1d ff 90 <0f> 0b 90 90 e9 5f fe ff ff e8 04 69 5e ff 90 48 b8 00
00 00 00 00  RSP: 0018:ffffc90003637b08 EFLAGS: 00010282  RAX:
0000000000000000 RBX: ffff88805f534140 RCX: ffffffff817a92c8  RDX:
ffff88807da99e00 RSI: ffffffff817a92d5 RDI: 0000000000000001  RBP:
ffff888033431ac0 R08: 0000000000000001 R09: 0000000000000000  R10:
0000000000000001 R11: 0000000000000001 R12: ffff888033431a00  R13:
ffff888033431ae4 R14: ffff888033184724 R15: dffffc0000000000  FS:
0000555580328500(0000) GS:ffff888124a62000(0000)
knlGS:0000000000000000  CS:  0010 DS: 0000 ES: 0000 CR0:
0000000080050033  CR2: 00007f71733743e0 CR3: 000000007f618000 CR4:
00000000003526f0  DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
0000000000000400  Call Trace:   <TASK>    sunrpc_exit_net+0x46/0x90
net/sunrpc/sunrpc_syms.c:76    ops_exit_list
net/core/net_namespace.c:200 [inline]    ops_undo_list+0x2eb/0xab0
net/core/net_namespace.c:253    setup_net+0x2e1/0x510
net/core/net_namespace.c:457    copy_net_ns+0x2a6/0x5f0
net/core/net_namespace.c:574    create_new_namespaces+0x3ea/0xa90
kernel/nsproxy.c:110    unshare_nsproxy_namespaces+0xc0/0x1f0
kernel/nsproxy.c:218    ksys_unshare+0x45b/0xa40 kernel/fork.c:3121
__do_sys_unshare kernel/fork.c:3192 [inline]    __se_sys_unshare
kernel/fork.c:3190 [inline]    __x64_sys_unshare+0x31/0x40
kernel/fork.c:3190    do_syscall_x64 arch/x86/entry/syscall_64.c:63
[inline]    do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f  RIP: 0033:0x7fa1a6b8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48
89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d
01 f0 ff ff 73 01 c  ---truncated---

This plugin only works with Tenable.ot.
Please visit https://www.tenable.com/products/tenable-ot for more information.");
  script_set_attribute(attribute:"see_also", value:"https://cert-portal.siemens.com/productcert/html/ssa-082556.html");
  script_set_attribute(attribute:"solution", value:
"Refer to the vendor advisory.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:S/C:N/I:N/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2025-38400");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_cwe_id(20);

  script_set_attribute(attribute:"vuln_publication_date", value:"2025/06/10");
  script_set_attribute(attribute:"patch_publication_date", value:"2025/06/10");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/03/23");

  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:siemens:simatic_s7-1500_cpu_firmware:3.1.5");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:siemens:siplus_s7-1500_cpu_firmware");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Tenable.ot");

  script_copyright(english:"This script is Copyright (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("tenable_ot_api_integration.nasl");
  script_require_keys("Tenable.ot/Siemens");

  exit(0);
}


include('tenable_ot_cve_funcs.inc');

get_kb_item_or_exit('Tenable.ot/Siemens');

var asset = tenable_ot::assets::get(vendor:'Siemens');

var vuln_cpes = {
    "cpe:/o:siemens:simatic_s7-1500_cpu_firmware:3.1.5" :
        {"versionStartIncluding" : "3.1.5", "family" : "S71500", "orderNumbers" : ['6ES7518-4AX00-1AC0', '6ES7518-4FX00-1AC0', '6ES7518-4AX00-1AB0', '6ES7518-4FX00-1AB0']},
    "cpe:/o:siemens:siplus_s7-1500_cpu_firmware" :
        {"family" : "S71500", "orderNumbers" : ['6AG1518-4AX00-4AC0']}
};

tenable_ot::cve::compare_and_report(asset:asset, cpes:vuln_cpes, severity:SECURITY_WARNING);