diff --git a/monkey/common/common_consts/validation_formats.py b/monkey/common/common_consts/validation_formats.py
index 2f04dbe21..41a460a8a 100644
--- a/monkey/common/common_consts/validation_formats.py
+++ b/monkey/common/common_consts/validation_formats.py
@@ -1,3 +1,5 @@
 # Defined in UI on ValidationFormats.js
 IP_RANGE = "ip-range"
 IP = "ip"
+VALID_RANSOMWARE_TARGET_PATH_LINUX = "valid-ransomware-target-path-linux"
+VALID_RANSOMWARE_TARGET_PATH_WINDOWS = "valid-ransomware-target-path-windows"
diff --git a/monkey/monkey_island/cc/services/config_schema/ransomware.py b/monkey/monkey_island/cc/services/config_schema/ransomware.py
index 9c445a833..64b986acb 100644
--- a/monkey/monkey_island/cc/services/config_schema/ransomware.py
+++ b/monkey/monkey_island/cc/services/config_schema/ransomware.py
@@ -1,3 +1,8 @@
+from common.common_consts.validation_formats import (
+    VALID_RANSOMWARE_TARGET_PATH_LINUX,
+    VALID_RANSOMWARE_TARGET_PATH_WINDOWS,
+)
+
 RANSOMWARE = {
     "title": "Ransomware",
     "type": "object",
@@ -27,6 +32,7 @@ RANSOMWARE = {
                         "linux_target_dir": {
                             "title": "Linux target directory",
                             "type": "string",
+                            "format": VALID_RANSOMWARE_TARGET_PATH_LINUX,
                             "default": "",
                             "description": "A path to a directory on Linux systems that contains "
                             "files that you will allow Infection Monkey to encrypt. If no "
@@ -35,6 +41,7 @@ RANSOMWARE = {
                         "windows_target_dir": {
                             "title": "Windows target directory",
                             "type": "string",
+                            "format": VALID_RANSOMWARE_TARGET_PATH_WINDOWS,
                             "default": "",
                             "description": "A path to a directory on Windows systems that contains "
                             "files that you will allow Infection Monkey to encrypt. If no "
diff --git a/monkey/monkey_island/cc/ui/src/components/configuration-components/ValidationErrorMessages.js b/monkey/monkey_island/cc/ui/src/components/configuration-components/ValidationErrorMessages.js
index a5782948a..3c7280f97 100644
--- a/monkey/monkey_island/cc/ui/src/components/configuration-components/ValidationErrorMessages.js
+++ b/monkey/monkey_island/cc/ui/src/components/configuration-components/ValidationErrorMessages.js
@@ -1,4 +1,6 @@
-import {IP, IP_RANGE} from './ValidationFormats';
+import {IP, IP_RANGE, VALID_RANSOMWARE_TARGET_PATH_LINUX, VALID_RANSOMWARE_TARGET_PATH_WINDOWS} from './ValidationFormats';
+
+let invalidDirMessage = 'Invalid directory. Path should be absolute or begin with an environment variable.';
 
 export default function transformErrors(errors) {
   return errors.map(error => {
@@ -8,6 +10,10 @@ export default function transformErrors(errors) {
       error.message = 'Invalid IP range, refer to description for valid examples.'
     } else if (error.name === 'format' && error.params.format === IP) {
       error.message = 'Invalid IP.'
+    } else if (error.name === 'format' && error.params.format === VALID_RANSOMWARE_TARGET_PATH_LINUX) {
+      error.message = invalidDirMessage
+    } else if (error.name === 'format' && error.params.format === VALID_RANSOMWARE_TARGET_PATH_WINDOWS) {
+      error.message = invalidDirMessage
     }
     return error;
   });
diff --git a/monkey/monkey_island/cc/ui/src/components/configuration-components/ValidationFormats.js b/monkey/monkey_island/cc/ui/src/components/configuration-components/ValidationFormats.js
index ff0b4706b..70d9f82fd 100644
--- a/monkey/monkey_island/cc/ui/src/components/configuration-components/ValidationFormats.js
+++ b/monkey/monkey_island/cc/ui/src/components/configuration-components/ValidationFormats.js
@@ -2,12 +2,31 @@ const ipRegex = '((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(25[0-5]|2[0-4][0
 const cidrNotationRegex = '([0-9]|1[0-9]|2[0-9]|3[0-2])'
 const hostnameRegex = '^([A-Za-z0-9]*[A-Za-z]+[A-Za-z0-9]*.?)*([A-Za-z0-9]*[A-Za-z]+[A-Za-z0-9]*)$'
 
+
+const linuxAbsolutePathRegex = /^\// // path starts with `/`
+const linuxPathStartsWithEnvVariableRegex = /^\$/ // path starts with `$`
+const linuxPathStartsWithTildeRegex = /^~/ // path starts with `~`
+
+
+const windowsAbsolutePathRegex = /^([A-Za-z]:(\\|\/))/ // path starts like `C:\` OR `C:/`
+const windowsEnvVarNonNumeric = '[A-Za-z#\\$\'\\(\\)\\*\\+,\\-\\.\\?@\\[\\]_`\\{\\}~ ]'
+const windowsPathStartsWithEnvVariableRegex = new RegExp(
+	`^%(${windowsEnvVarNonNumeric}+(${windowsEnvVarNonNumeric}|\\d)*)%`
+) // path starts like `$` OR `%abc%`
+const windowsUncPathRegex = /^\\{2}/ // Path starts like `\\`
+const emptyRegex = /^$/
+
+
 export const IP_RANGE = 'ip-range';
 export const IP = 'ip';
+export const VALID_RANSOMWARE_TARGET_PATH_LINUX = 'valid-ransomware-target-path-linux'
+export const VALID_RANSOMWARE_TARGET_PATH_WINDOWS = 'valid-ransomware-target-path-windows'
 
 export const formValidationFormats = {
   [IP_RANGE]: buildIpRangeRegex(),
-  [IP]: buildIpRegex()
+  [IP]: buildIpRegex(),
+  [VALID_RANSOMWARE_TARGET_PATH_LINUX]: buildValidRansomwarePathLinuxRegex(),
+  [VALID_RANSOMWARE_TARGET_PATH_WINDOWS]: buildValidRansomwarePathWindowsRegex()
 };
 
 function buildIpRangeRegex(){
@@ -22,3 +41,21 @@ function buildIpRangeRegex(){
 function buildIpRegex(){
   return new RegExp('^'+ipRegex+'$')
 }
+
+function buildValidRansomwarePathLinuxRegex() {
+  return new RegExp([
+		emptyRegex.source,
+    linuxAbsolutePathRegex.source,
+    linuxPathStartsWithEnvVariableRegex.source,
+    linuxPathStartsWithTildeRegex.source
+  ].join('|'))
+}
+
+function buildValidRansomwarePathWindowsRegex() {
+  return new RegExp([
+		emptyRegex.source,
+    windowsAbsolutePathRegex.source,
+    windowsPathStartsWithEnvVariableRegex.source,
+    windowsUncPathRegex.source
+  ].join('|'))
+}