YARA · SEKOIA.IO Community

SEKOIA_Apt_Icepeony_Icecache

Detects IceCache backdoor

APT / threat actorIce CacheSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X

Author: Sekoia.io
Date: 2024-10-21
Modified: 2024-12-19
Score / Quality: 75 / 80

What this rule detects

Detects IceCache backdoor

Associated malware family: Ice Cache.

Targets: Windows PE.

It defines 17 patterns (17 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

apt-icepeony-icecache.yarDetection Rule License 1.1

rule SEKOIA_Apt_Icepeony_Icecache : FILE
{
	meta:
		description = "Detects IceCache backdoor"
		author = "Sekoia.io"
		id = "3135c70e-c925-4d26-beed-09424fc0c153"
		date = "2024-10-21"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/apt_icepeony_icecache.yar#L1-L46"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		hash = "38708c33dafb5625ddde1030a7efa7db"
		hash = "1e102c8909b2bf71c626b81f7526ee01"
		hash = "34bc3c586a48f836b00aff59fe891b30"
		hash = "cd906f4cef84dddeb644b06777474b2e"
		hash = "add23fedfbf238f51173796f3feb12af"
		hash = "25b8daaa5e9c5f8820261d7ebf79f3cd"
		hash = "7fd45cc1de1230c916d5f547a9fc725c"
		hash = "e6e4060e838d7af5f13ad64258d5db0c"
		hash = "87dfc911885420380bea0cf74c8160d3"
		hash = "bd15103b300cad635191972330913d17"
		hash = "a8119b7803a6e0b8aed6bc74d9062b7f"
		hash = "e1bc3efc33b57c9e1e6d37e5011228f2"
		hash = "e1233a5f613aafec2c28133e810f536d"
		hash = "fe88a5b91841b25b4bafa08d42faab22"
		logic_hash = "db82489e1a1eb55960b7a8fd3e6f52db526295ed4e5b90ddea826c5be5f9a1c4"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$ = "Source Response Empty!"
		$ = "Source Response Len:"
		$ = "GetFromSource:"
		$ = "Failed add header!"
		$ = "Failed receive response:"
		$ = "Error: Status Code :"
		$ = "WinHttpAddRequestHeaders"
		$ = "X-FORWARDED-HOST:"
		$ = "PROXY_DEL_CONTENT"
		$ = "PROXY_CLEAR_CONTENT"
		$ = "PROXY_SET_JS"
		$ = "PROXY_GET_JS"
		$ = "PROXY_ALLOW_PC"
		$ = "Parse IP failed :"
		$ = "Clear Proxy Contents Success!"
		$ = "FILE_UPLOAD"
		$ = "FILE_DOWNLOAD"

	condition:
		uint16be( 0 ) == 0x4d5a and filesize < 1MB and 6 of them
}

Strings (17 patterns)

Identifier	Type	Value
$	text	"Source Response Empty!"
$	text	"Source Response Len:"
$	text	"GetFromSource:"
$	text	"Failed add header!"
$	text	"Failed receive response:"
$	text	"Error: Status Code :"
$	text	"WinHttpAddRequestHeaders"
$	text	"X-FORWARDED-HOST:"
$	text	"PROXY_DEL_CONTENT"
$	text	"PROXY_CLEAR_CONTENT"
$	text	"PROXY_SET_JS"
$	text	"PROXY_GET_JS"
$	text	"PROXY_ALLOW_PC"
$	text	"Parse IP failed :"
$	text	"Clear Proxy Contents Success!"
$	text	"FILE_UPLOAD"
$	text	"FILE_DOWNLOAD"

Condition

uint16be( 0 ) == 0x4d5a and filesize < 1MB and 6 of them

In plain words (Heuristic)

The file must start with “MZ” — a Windows executable (PE).
The file must be smaller than 1MB (a cheap guard that skips large files).
At least 6 patterns in the rule must match.

Test this rule in your browser

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Drop a file here or click to chooseScanned locally with YARA-X. Files up to 200 MB.

Open in editor

References

https://github.com/SEKOIA-IO/Community

Sample hashes

Hashes of samples the author lists in the rule's meta (look them up in your threat-intelligence platform).

38708c33dafb5625ddde1030a7efa7db
1e102c8909b2bf71c626b81f7526ee01
34bc3c586a48f836b00aff59fe891b30
cd906f4cef84dddeb644b06777474b2e
add23fedfbf238f51173796f3feb12af
25b8daaa5e9c5f8820261d7ebf79f3cd
7fd45cc1de1230c916d5f547a9fc725c
e6e4060e838d7af5f13ad64258d5db0c
87dfc911885420380bea0cf74c8160d3
bd15103b300cad635191972330913d17
a8119b7803a6e0b8aed6bc74d9062b7f
e1bc3efc33b57c9e1e6d37e5011228f2
e1233a5f613aafec2c28133e810f536d
fe88a5b91841b25b4bafa08d42faab22

Licence & attribution

Author: Sekoia.io

Source repository: SEKOIA.IO Community @ a438a5901a

Licence: Detection Rule License 1.1 (repository licence)

Original rule

Mirrored via YARA Forge 20260927, which prefixes rule names with the source and adds normalised meta fields.

Rule id: 3135c70e-c925-4d26-beed-09424fc0c153

Metadata

version	1.0
classification	TLP:CLEAR

Tags:FILE

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